feat: remove unused imports

frontend/app_flowy/packages/flowy_editor/lib/render/rich_text/flowy_rich_text.dart

@@ -255,6 +255,10 @@ class _FlowyRichTextState extends State<FlowyRichText> with Selectable {
     return Rect.zero;
   }
 
+  Offset localToGlobal(Offset offset) {
+    return _renderParagraph.localToGlobal(offset);
+  }
+
   TextSpan get _decorateTextSpanWithGlobalStyle => TextSpan(
         children: _textSpan.children
             ?.whereType<TextSpan>()

frontend/app_flowy/packages/flowy_editor/lib/service/internal_key_event_handlers/arrow_keys_handler.dart

@@ -2,7 +2,6 @@ import 'package:flowy_editor/document/node.dart';
 import 'package:flowy_editor/document/position.dart';
 import 'package:flowy_editor/service/keyboard_service.dart';
 import 'package:flowy_editor/document/selection.dart';
-import 'package:flowy_editor/extensions/node_extensions.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';