* chore: move selectionRects to editorState
* chore: delete unused attributeKey font
* feat: refactor showLinkMenu and LinkMenu
* feat: replace old linkMenu
* feat: add text color toolbar item
- separate text color and highlight color item in toolbar
- renaming in BuiltInAttributeKey(color -> textColor, backgroundColor -> highlightColor)
- add text color and highlight color attribute in example.json
- add icons for text color and highlight color in the toolbar
* feat: add highlight color item in toolbar
- add clear highlight color button
- add onDismiss in ColorPicker to remove the overlay after remove highlight color
* chore: delete old ColorPicker
* test: migrate link menu test
* chore: remove editorStyle from color menu and color picker
* test: add color picker test
* feat: remove editor style from link menu
- add utils function and widgets for overlay
- organize utils folder
- add constant text into AppFlowyEditorLocalizations
- improve pop up menu style
* feat: add show link menu command shortcut
- refactor CommandShortcutEventHandler
- update related callback
* feat: add showTextColorMenuCommand and showHighlightColorMenuCommand
* fix: fix merge error in example.json
* refactor: reorganize the file hierarchy
* refactor: migrate format_style_handler_test.dart
- delete format_style_handler_test.dart
- migrate to markdown_commands_test.dart
- move highlight test outside of markdown_commands_test
* feat: delete show menu type command shortcut and their tooltip
* fix: fix tooltip text
* chore: delete context from CommandShortcutEventHandler
* feat: add command shortcut for link menu
* test: add show link menu command test
