refactor: renamed helper.dart to notification_helper.dart

frontend/app_flowy/lib/user/application/user_listener.dart

@@ -3,7 +3,7 @@ import 'package:dartz/dartz.dart';
 import 'package:flowy_sdk/protobuf/flowy-folder-data-model/workspace.pb.dart';
 import 'package:flowy_sdk/protobuf/flowy-error/errors.pb.dart';
 import 'dart:typed_data';
-import 'package:app_flowy/core/helper.dart';
+import 'package:app_flowy/core/notification_helper.dart';
 import 'package:flowy_infra/notifier.dart';
 import 'package:flowy_sdk/protobuf/dart-notify/protobuf.dart';
 import 'package:flowy_sdk/protobuf/flowy-folder/dart_notification.pb.dart';

frontend/app_flowy/lib/workspace/application/app/app_listener.dart

@@ -1,7 +1,7 @@
 import 'dart:async';
 import 'dart:typed_data';
 import 'package:dartz/dartz.dart';
-import 'package:app_flowy/core/helper.dart';
+import 'package:app_flowy/core/notification_helper.dart';
 import 'package:flowy_sdk/log.dart';
 import 'package:flowy_sdk/protobuf/dart-notify/subject.pb.dart';
 import 'package:flowy_sdk/protobuf/flowy-error/errors.pb.dart';

frontend/app_flowy/lib/workspace/application/trash/trash_listener.dart

@@ -1,7 +1,7 @@
 import 'dart:async';
 import 'dart:typed_data';
 import 'package:dartz/dartz.dart';
-import 'package:app_flowy/core/helper.dart';
+import 'package:app_flowy/core/notification_helper.dart';
 import 'package:flowy_sdk/protobuf/dart-notify/subject.pb.dart';
 import 'package:flowy_sdk/protobuf/flowy-folder/dart_notification.pb.dart';
 import 'package:flowy_sdk/protobuf/flowy-error/errors.pb.dart';

frontend/app_flowy/lib/workspace/application/view/view_listener.dart

@@ -1,6 +1,6 @@
 import 'dart:async';
 import 'dart:typed_data';
-import 'package:app_flowy/core/helper.dart';
+import 'package:app_flowy/core/notification_helper.dart';
 import 'package:dartz/dartz.dart';
 import 'package:flowy_sdk/protobuf/dart-notify/subject.pb.dart';
 import 'package:flowy_sdk/protobuf/flowy-folder-data-model/view.pb.dart';

frontend/app_flowy/lib/workspace/application/workspace/workspace_listener.dart

@@ -1,7 +1,7 @@
 import 'dart:async';
 import 'dart:typed_data';
 
-import 'package:app_flowy/core/helper.dart';
+import 'package:app_flowy/core/notification_helper.dart';
 import 'package:dartz/dartz.dart';
 import 'package:flowy_sdk/log.dart';
 import 'package:flowy_sdk/protobuf/dart-notify/subject.pb.dart';