chore: update project references and add Citron copyright

- Replaced all references to the old project name with Citron.
- Added Citron copyright information alongside existing notices in all files.

src/citron/multiplayer/client_room.h

@@ -3,7 +3,7 @@
 
 #pragma once
 
-#include "yuzu/multiplayer/chat_room.h"
+#include "citron/multiplayer/chat_room.h"
 
 namespace Ui {
 class ClientRoom;