Add lit components localization

Localization is performed via the @lit/localize package, which has been
integrated into the repo. A I18nLitElement class which extends
LitElement has been included, which automatically sets up the
localization.

This CL also introduces localization to the flattenThreads feature.

Fixed: twpowertools:157
Change-Id: If01540b9c8d70876a648aa002a1e0a5bede8f383
diff --git a/src/lit-locales/source/ar.xlf b/src/lit-locales/source/ar.xlf
new file mode 100644
index 0000000..a029342
--- /dev/null
+++ b/src/lit-locales/source/ar.xlf
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
+<file target-language="ar" source-language="en" original="lit-localize-inputs" datatype="plaintext">
+<body>
+<trans-unit id="s0b7ae9543c001867">
+  <source>Reply</source>
+  <note from="lit-localize">Button which is used to open the reply box.</note>
+</trans-unit>
+<trans-unit id="sa5ef80b4bb9b39f8">
+  <source>Less</source>
+  <note from="lit-localize">Button to collapse the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+<trans-unit id="s37a9e8aec5713460">
+  <source>More</source>
+  <note from="lit-localize">Button to expand the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+</body>
+</file>
+</xliff>
diff --git a/src/lit-locales/source/ca.xlf b/src/lit-locales/source/ca.xlf
new file mode 100644
index 0000000..bac628b
--- /dev/null
+++ b/src/lit-locales/source/ca.xlf
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
+<file target-language="ca" source-language="en" original="lit-localize-inputs" datatype="plaintext">
+<body>
+<trans-unit id="s0b7ae9543c001867">
+  <source>Reply</source>
+  <note from="lit-localize">Button which is used to open the reply box.</note>
+</trans-unit>
+<trans-unit id="sa5ef80b4bb9b39f8">
+  <source>Less</source>
+  <note from="lit-localize">Button to collapse the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+<trans-unit id="s37a9e8aec5713460">
+  <source>More</source>
+  <note from="lit-localize">Button to expand the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+</body>
+</file>
+</xliff>
diff --git a/src/lit-locales/source/de.xlf b/src/lit-locales/source/de.xlf
new file mode 100644
index 0000000..fc2ac15
--- /dev/null
+++ b/src/lit-locales/source/de.xlf
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
+<file target-language="de" source-language="en" original="lit-localize-inputs" datatype="plaintext">
+<body>
+<trans-unit id="s0b7ae9543c001867">
+  <source>Reply</source>
+  <note from="lit-localize">Button which is used to open the reply box.</note>
+</trans-unit>
+<trans-unit id="sa5ef80b4bb9b39f8">
+  <source>Less</source>
+  <note from="lit-localize">Button to collapse the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+<trans-unit id="s37a9e8aec5713460">
+  <source>More</source>
+  <note from="lit-localize">Button to expand the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+</body>
+</file>
+</xliff>
diff --git a/src/lit-locales/source/es.xlf b/src/lit-locales/source/es.xlf
new file mode 100644
index 0000000..feb09aa
--- /dev/null
+++ b/src/lit-locales/source/es.xlf
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
+<file target-language="es" source-language="en" original="lit-localize-inputs" datatype="plaintext">
+<body>
+<trans-unit id="s0b7ae9543c001867">
+  <source>Reply</source>
+  <note from="lit-localize">Button which is used to open the reply box.</note>
+</trans-unit>
+<trans-unit id="sa5ef80b4bb9b39f8">
+  <source>Less</source>
+  <note from="lit-localize">Button to collapse the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+<trans-unit id="s37a9e8aec5713460">
+  <source>More</source>
+  <note from="lit-localize">Button to expand the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+</body>
+</file>
+</xliff>
diff --git a/src/lit-locales/source/fr.xlf b/src/lit-locales/source/fr.xlf
new file mode 100644
index 0000000..4bcddaf
--- /dev/null
+++ b/src/lit-locales/source/fr.xlf
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
+<file target-language="fr" source-language="en" original="lit-localize-inputs" datatype="plaintext">
+<body>
+<trans-unit id="s0b7ae9543c001867">
+  <source>Reply</source>
+  <note from="lit-localize">Button which is used to open the reply box.</note>
+</trans-unit>
+<trans-unit id="sa5ef80b4bb9b39f8">
+  <source>Less</source>
+  <note from="lit-localize">Button to collapse the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+<trans-unit id="s37a9e8aec5713460">
+  <source>More</source>
+  <note from="lit-localize">Button to expand the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+</body>
+</file>
+</xliff>
diff --git a/src/lit-locales/source/id.xlf b/src/lit-locales/source/id.xlf
new file mode 100644
index 0000000..d305689
--- /dev/null
+++ b/src/lit-locales/source/id.xlf
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
+<file target-language="id" source-language="en" original="lit-localize-inputs" datatype="plaintext">
+<body>
+<trans-unit id="s0b7ae9543c001867">
+  <source>Reply</source>
+  <note from="lit-localize">Button which is used to open the reply box.</note>
+</trans-unit>
+<trans-unit id="sa5ef80b4bb9b39f8">
+  <source>Less</source>
+  <note from="lit-localize">Button to collapse the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+<trans-unit id="s37a9e8aec5713460">
+  <source>More</source>
+  <note from="lit-localize">Button to expand the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+</body>
+</file>
+</xliff>
diff --git a/src/lit-locales/source/it.xlf b/src/lit-locales/source/it.xlf
new file mode 100644
index 0000000..ba1eb1a
--- /dev/null
+++ b/src/lit-locales/source/it.xlf
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
+<file target-language="it" source-language="en" original="lit-localize-inputs" datatype="plaintext">
+<body>
+<trans-unit id="s0b7ae9543c001867">
+  <source>Reply</source>
+  <note from="lit-localize">Button which is used to open the reply box.</note>
+</trans-unit>
+<trans-unit id="sa5ef80b4bb9b39f8">
+  <source>Less</source>
+  <note from="lit-localize">Button to collapse the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+<trans-unit id="s37a9e8aec5713460">
+  <source>More</source>
+  <note from="lit-localize">Button to expand the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+</body>
+</file>
+</xliff>
diff --git a/src/lit-locales/source/ja.xlf b/src/lit-locales/source/ja.xlf
new file mode 100644
index 0000000..1e8d38e
--- /dev/null
+++ b/src/lit-locales/source/ja.xlf
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
+<file target-language="ja" source-language="en" original="lit-localize-inputs" datatype="plaintext">
+<body>
+<trans-unit id="s0b7ae9543c001867">
+  <source>Reply</source>
+  <note from="lit-localize">Button which is used to open the reply box.</note>
+</trans-unit>
+<trans-unit id="sa5ef80b4bb9b39f8">
+  <source>Less</source>
+  <note from="lit-localize">Button to collapse the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+<trans-unit id="s37a9e8aec5713460">
+  <source>More</source>
+  <note from="lit-localize">Button to expand the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+</body>
+</file>
+</xliff>
diff --git a/src/lit-locales/source/ko.xlf b/src/lit-locales/source/ko.xlf
new file mode 100644
index 0000000..6a3d938
--- /dev/null
+++ b/src/lit-locales/source/ko.xlf
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
+<file target-language="ko" source-language="en" original="lit-localize-inputs" datatype="plaintext">
+<body>
+<trans-unit id="s0b7ae9543c001867">
+  <source>Reply</source>
+  <note from="lit-localize">Button which is used to open the reply box.</note>
+</trans-unit>
+<trans-unit id="sa5ef80b4bb9b39f8">
+  <source>Less</source>
+  <note from="lit-localize">Button to collapse the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+<trans-unit id="s37a9e8aec5713460">
+  <source>More</source>
+  <note from="lit-localize">Button to expand the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+</body>
+</file>
+</xliff>
diff --git a/src/lit-locales/source/pl.xlf b/src/lit-locales/source/pl.xlf
new file mode 100644
index 0000000..8d1b568
--- /dev/null
+++ b/src/lit-locales/source/pl.xlf
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
+<file target-language="pl" source-language="en" original="lit-localize-inputs" datatype="plaintext">
+<body>
+<trans-unit id="s0b7ae9543c001867">
+  <source>Reply</source>
+  <note from="lit-localize">Button which is used to open the reply box.</note>
+</trans-unit>
+<trans-unit id="sa5ef80b4bb9b39f8">
+  <source>Less</source>
+  <note from="lit-localize">Button to collapse the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+<trans-unit id="s37a9e8aec5713460">
+  <source>More</source>
+  <note from="lit-localize">Button to expand the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+</body>
+</file>
+</xliff>
diff --git a/src/lit-locales/source/pt_BR.xlf b/src/lit-locales/source/pt_BR.xlf
new file mode 100644
index 0000000..685d940
--- /dev/null
+++ b/src/lit-locales/source/pt_BR.xlf
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
+<file target-language="pt_BR" source-language="en" original="lit-localize-inputs" datatype="plaintext">
+<body>
+<trans-unit id="s0b7ae9543c001867">
+  <source>Reply</source>
+  <note from="lit-localize">Button which is used to open the reply box.</note>
+</trans-unit>
+<trans-unit id="sa5ef80b4bb9b39f8">
+  <source>Less</source>
+  <note from="lit-localize">Button to collapse the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+<trans-unit id="s37a9e8aec5713460">
+  <source>More</source>
+  <note from="lit-localize">Button to expand the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+</body>
+</file>
+</xliff>
diff --git a/src/lit-locales/source/ru.xlf b/src/lit-locales/source/ru.xlf
new file mode 100644
index 0000000..7eaa9fc
--- /dev/null
+++ b/src/lit-locales/source/ru.xlf
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
+<file target-language="ru" source-language="en" original="lit-localize-inputs" datatype="plaintext">
+<body>
+<trans-unit id="s0b7ae9543c001867">
+  <source>Reply</source>
+  <note from="lit-localize">Button which is used to open the reply box.</note>
+</trans-unit>
+<trans-unit id="sa5ef80b4bb9b39f8">
+  <source>Less</source>
+  <note from="lit-localize">Button to collapse the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+<trans-unit id="s37a9e8aec5713460">
+  <source>More</source>
+  <note from="lit-localize">Button to expand the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+</body>
+</file>
+</xliff>
diff --git a/src/lit-locales/source/th.xlf b/src/lit-locales/source/th.xlf
new file mode 100644
index 0000000..b13edb4
--- /dev/null
+++ b/src/lit-locales/source/th.xlf
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
+<file target-language="th" source-language="en" original="lit-localize-inputs" datatype="plaintext">
+<body>
+<trans-unit id="s0b7ae9543c001867">
+  <source>Reply</source>
+  <note from="lit-localize">Button which is used to open the reply box.</note>
+</trans-unit>
+<trans-unit id="sa5ef80b4bb9b39f8">
+  <source>Less</source>
+  <note from="lit-localize">Button to collapse the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+<trans-unit id="s37a9e8aec5713460">
+  <source>More</source>
+  <note from="lit-localize">Button to expand the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+</body>
+</file>
+</xliff>
diff --git a/src/lit-locales/source/tr.xlf b/src/lit-locales/source/tr.xlf
new file mode 100644
index 0000000..c6468f2
--- /dev/null
+++ b/src/lit-locales/source/tr.xlf
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
+<file target-language="tr" source-language="en" original="lit-localize-inputs" datatype="plaintext">
+<body>
+<trans-unit id="s0b7ae9543c001867">
+  <source>Reply</source>
+  <note from="lit-localize">Button which is used to open the reply box.</note>
+</trans-unit>
+<trans-unit id="sa5ef80b4bb9b39f8">
+  <source>Less</source>
+  <note from="lit-localize">Button to collapse the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+<trans-unit id="s37a9e8aec5713460">
+  <source>More</source>
+  <note from="lit-localize">Button to expand the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+</body>
+</file>
+</xliff>
diff --git a/src/lit-locales/source/vi.xlf b/src/lit-locales/source/vi.xlf
new file mode 100644
index 0000000..674c7dc
--- /dev/null
+++ b/src/lit-locales/source/vi.xlf
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xliff version="1.2" xmlns="urn:oasis:names:tc:xliff:document:1.2">
+<file target-language="vi" source-language="en" original="lit-localize-inputs" datatype="plaintext">
+<body>
+<trans-unit id="s0b7ae9543c001867">
+  <source>Reply</source>
+  <note from="lit-localize">Button which is used to open the reply box.</note>
+</trans-unit>
+<trans-unit id="sa5ef80b4bb9b39f8">
+  <source>Less</source>
+  <note from="lit-localize">Button to collapse the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+<trans-unit id="s37a9e8aec5713460">
+  <source>More</source>
+  <note from="lit-localize">Button to expand the quote message (used in the flatten threads feature).</note>
+</trans-unit>
+</body>
+</file>
+</xliff>