chore: format dart code

Author: LucasXu0

frontend/app_flowy/packages/appflowy_editor/lib/src/service/editor_service.dart

@@ -1,7 +1,6 @@
 import 'package:appflowy_editor/appflowy_editor.dart';
 import 'package:appflowy_editor/src/flutter/overlay.dart';
 import 'package:appflowy_editor/src/render/image/image_node_builder.dart';
-import 'package:appflowy_editor/src/render/toolbar/toolbar_item.dart';
 import 'package:appflowy_editor/src/service/shortcut_event/built_in_shortcut_events.dart';
 import 'package:flutter/material.dart' hide Overlay, OverlayEntry;
 

frontend/app_flowy/packages/appflowy_editor/lib/src/service/toolbar_service.dart

@@ -1,5 +1,4 @@
 import 'package:appflowy_editor/src/flutter/overlay.dart';
-import 'package:appflowy_editor/src/render/toolbar/toolbar_item.dart';
 import 'package:flutter/material.dart' hide Overlay, OverlayEntry;
 
 import 'package:appflowy_editor/appflowy_editor.dart';

frontend/app_flowy/packages/appflowy_editor/test/service/toolbar_service_test.dart

@@ -1,5 +1,4 @@
 import 'package:appflowy_editor/appflowy_editor.dart';
-import 'package:appflowy_editor/src/render/toolbar/toolbar_item.dart';
 import 'package:appflowy_editor/src/render/toolbar/toolbar_item_widget.dart';
 import 'package:appflowy_editor/src/render/toolbar/toolbar_widget.dart';
 import 'package:flutter_test/flutter_test.dart';