refactor(cc-dark-theme): organize styles in several files

Until now we had a single file for the dark theme styles with ~2500
lines, with several sections which were marked with CSS comments.

This CL separates this file into several ones to improve its
maintainability, using the folder structure suggested by
https://sass-guidelin.es/#architecture.

Fixed: twpowertools:21
Change-Id: I0c1741f58b470085c0a499b32aa64feb43d8ad31
diff --git a/src/ccDarkTheme/components/_query-builder.scss b/src/ccDarkTheme/components/_query-builder.scss
new file mode 100644
index 0000000..b7551b7
--- /dev/null
+++ b/src/ccDarkTheme/components/_query-builder.scss
@@ -0,0 +1,19 @@
+// Filters (ec-query-builder)
+material-condition-builder .compound-condition-operator {
+  color: var(--TWPT-secondary-text)!important;
+}
+
+material-condition-builder .compound-condition-operator:is(::before, ::after) {
+  border-left-color: rgba(255, 255, 255, .20)!important;
+}
+
+material-condition-builder .add-button,
+    ec-query-builder .save-filter-button:not([disabled]) {
+  color: var(--TWPT-blue-A100)!important;
+}
+
+material-condition-builder .add-condition,
+    ec-query-builder .close-button {
+  background-color: var(--TWPT-interop-blue)!important;
+  color: #1f1f1f!important;
+}