Add language dropdown to compose in web UI (#18420)

app/javascript/mastodon/locales/defaultMessages.json

@@ -1257,6 +1257,23 @@
     ],
     "path": "app/javascript/mastodon/features/compose/components/emoji_picker_dropdown.json"
   },
+  {
+    "descriptors": [
+      {
+        "defaultMessage": "Change language",
+        "id": "compose.language.change"
+      },
+      {
+        "defaultMessage": "Search languages...",
+        "id": "compose.language.search"
+      },
+      {
+        "defaultMessage": "Clear",
+        "id": "emoji_button.clear"
+      }
+    ],
+    "path": "app/javascript/mastodon/features/compose/components/language_dropdown.json"
+  },
   {
     "descriptors": [
       {

app/javascript/mastodon/locales/en.json

@@ -92,6 +92,8 @@
   "community.column_settings.local_only": "Local only",
   "community.column_settings.media_only": "Media Only",
   "community.column_settings.remote_only": "Remote only",
+  "compose.language.change": "Change language",
+  "compose.language.search": "Search languages...",
   "compose_form.direct_message_warning_learn_more": "Learn more",
   "compose_form.encryption_warning": "Posts on Mastodon are not end-to-end encrypted. Do not share any dangerous information over Mastodon.",
   "compose_form.hashtag_warning": "This post won't be listed under any hashtag as it is unlisted. Only public posts can be searched by hashtag.",
@@ -147,6 +149,7 @@
   "embed.instructions": "Embed this post on your website by copying the code below.",
   "embed.preview": "Here is what it will look like:",
   "emoji_button.activity": "Activity",
+  "emoji_button.clear": "Clear",
   "emoji_button.custom": "Custom",
   "emoji_button.flags": "Flags",
   "emoji_button.food": "Food & Drink",