[Frontend] add X links to About and Help (#272)

Based off the recent addition of revolt links.
Authored-by: Bix bix@bixed.xyz
Signed-off-by: Bix bix@bixed.xyz

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/272
Reviewed-by: crueter <crueter@eden-emu.dev>
Co-authored-by: Bix <bix@bixed.xyz>
Co-committed-by: Bix <bix@bixed.xyz>

src/yuzu/main.h

@@ -347,6 +347,7 @@ private slots:
     void OnOpenFAQ();
     void OnOpenDiscord();
     void OnOpenRevolt();
+    void OnOpenX();
 
     /// Called whenever a user selects a game in the game list widget.
     void OnGameListLoadFile(QString game_path, u64 program_id);