refactored broad range of the application, split files, modularized calendar and file views, centralized bottom sheets and clipboard handling, and implemented unit test coverage

lib/api/marianumcloud/talk/chat/get_chat_response.dart

@@ -1,6 +1,6 @@
-import 'package:jiffy/jiffy.dart';
 import 'package:json_annotation/json_annotation.dart';
 
+import '../../../../extensions/date_time.dart';
 import '../../../api_response.dart';
 import '../room/get_room_response.dart';
 
@@ -63,7 +63,7 @@ class GetChatResponseObject {
 
   static GetChatResponseObject getDateDummy(int timestamp) {
     var elementDate = DateTime.fromMillisecondsSinceEpoch(timestamp * 1000);
-    return getTextDummy(Jiffy.parseFromDateTime(elementDate).format(pattern: 'dd.MM.yyyy'));
+    return getTextDummy(elementDate.formatDate());
   }
 
   static GetChatResponseObject getTextDummy(String text) => GetChatResponseObject(