Restructure unhandled buttons

lib/screen/pages/talk/chatList.dart

@@ -5,6 +5,7 @@ import 'package:jiffy/jiffy.dart';
 import 'package:marianum_mobile/api/marianumcloud/talk/chat/richObjectStringProcessor.dart';
 import 'package:marianum_mobile/api/marianumcloud/talk/room/getRoomResponse.dart';
 import 'package:marianum_mobile/data/chatList/chatListProps.dart';
+import 'package:marianum_mobile/widget/unimplementedDialog.dart';
 import 'package:persistent_bottom_nav_bar/persistent_tab_view.dart';
 import 'package:provider/provider.dart';
 import 'package:shared_preferences/shared_preferences.dart';
@@ -43,7 +44,9 @@ class _ChatListState extends State<ChatList> {
         actions: [
           IconButton(
             icon: const Icon(Icons.search),
-            onPressed: () => {},
+            onPressed: () => {
+              UnimplementedDialog.show(context)
+            },
           )
         ],
       ),