Add option to force disable SMEI_UNIFIED_PROFILES

Proposed here:
https://groups.google.com/g/twpowertools-discuss/c/QSOXU8IbrYU

Fixes: #47
Change-Id: I05caf5248cec1121ee083362910f81c484bfb3b2
diff --git a/src/common/common.js b/src/common/common.js
index f897837..9212389 100644
--- a/src/common/common.js
+++ b/src/common/common.js
@@ -76,6 +76,10 @@
     defaultValue: false,
     context: 'options',
   },
+  'disableunifiedprofiles': {
+    defaultValue: false,
+    context: 'options',
+  },
 
   // Experiments:
   'threadlistavatars': {