content: remove MessageUnicodeEmoji widget

This widget displayed the emoji name as a fallback in a bordered
container. But now that we rely on TextSpan to display the emoji
codepoints text, we can't reliably determine the fallback condition
_for now_.

Author: rajveermalviya

lib/widgets/content.dart

@@ -619,22 +619,6 @@ class UserMention extends StatelessWidget {
 //     borderRadius: BorderRadius.all(Radius.circular(3))));
 }
 
-class MessageUnicodeEmoji extends StatelessWidget {
-  const MessageUnicodeEmoji({super.key, required this.node});
-
-  final UnicodeEmojiNode node;
-
-  @override
-  Widget build(BuildContext context) {
-    // TODO(#58) get spritesheet and show actual emoji glyph
-    return Container(
-      padding: const EdgeInsets.all(2),
-      decoration: BoxDecoration(
-        color: Colors.white, border: Border.all(color: Colors.purple)),
-      child: Text(node.emojiName));
-  }
-}
-
 class MessageImageEmoji extends StatelessWidget {
   const MessageImageEmoji({super.key, required this.node});