replaced account data singleton with a session model

lib/view/pages/talk/widgets/chat_tile.dart

@@ -9,9 +9,9 @@ import '../../../../api/marianumcloud/talk/room/get_room_response.dart';
 import '../../../../api/marianumcloud/talk/room/notification_level.dart';
 import '../../../../api/marianumcloud/talk/set_read_marker/set_read_marker.dart';
 import '../../../../extensions/date_time.dart';
-import '../../../../model/account_data.dart';
 import '../../../../notification/notification_tasks.dart';
 import '../../../../routing/app_routes.dart';
+import '../../../../session/session_manager.dart';
 import '../../../../state/app/modules/chat/bloc/chat_bloc.dart';
 import '../../../../state/app/modules/chat_list/bloc/chat_list_bloc.dart';
 import '../../../../utils/haptics.dart';
@@ -53,13 +53,9 @@ class _ChatTileState extends State<ChatTile> {
   @override
   void initState() {
     super.initState();
-    AccountData().waitForPopulation().then((_) {
+    SessionManager().waitForLoad().then((session) {
       if (!mounted) return;
-      setState(
-        () => selfUsername = AccountData().isPopulated()
-            ? AccountData().getUsername()
-            : null,
-      );
+      setState(() => selfUsername = session?.nextcloud?.username);
     });
   }