chore: clean unnecessary todos (#3018)

frontend/appflowy_flutter/integration_test/document/edit_document_test.dart

@@ -99,7 +99,6 @@ void main() {
   });
 }
 
-// TODO(Lucas.Xu): there're no shorctcuts for underline, format code yet.
 const _sample = r'''
 # Heading 1
 ## Heading 2

frontend/appflowy_flutter/lib/plugins/document/presentation/editor_plugins/outline/outline_block_component.dart

@@ -165,7 +165,7 @@ class OutlineItemWidget extends StatelessWidget {
     final style = textStyle.href.combine(textStyle.text);
     return FlowyHover(
       style: HoverStyle(
-        hoverColor: Colors.grey.withOpacity(0.2), // TODO: use theme color.
+        hoverColor: Theme.of(context).hoverColor,
       ),
       child: GestureDetector(
         onTap: () => updateBlockSelection(context),