Switch from EmojiOne to Twemoji, different emoji picker (#5046)

* Switch from EmojiOne to Twemoji, different emoji picker

* Make emoji-mart use a local spritesheet

* Fix emojify test

* yarn manage:translations

app/javascript/styles/application.scss

@@ -15,6 +15,7 @@
 @import 'accounts';
 @import 'stream_entries';
 @import 'components';
+@import 'emoji_picker';
 @import 'about';
 @import 'tables';
 @import 'admin';