* Add pluggable AI actions menu with rewrite submenu and plugin extension point
* Use cascading hover popover for AI actions submenus
* Fix lint errors in AI actions menu and related files
* Update i18n strings for AI actions menu
* Fix coding guideline violations in AI actions menu and tests
* Fix spacing
* Fix stylelint errors in use_rewrite.scss
* Support ReactNode for AI action menu item text
* Fix empty menu guard, keyboard a11y, and rewrite follow-up placeholder
* Hide rewrite actions while a rewrite is in progress
* Remove subMenuHeader from plugin API and pass isRHS context to plugin components
* Support simple click actions in AI action menu plugin API
* Fix import order in ai_actions_menu tests
* Flip AI actions submenu to open left when insufficient space on right
Adapts the viewport-aware positioning pattern from the existing SubMenu
component so the cascading submenu renders on the side with more space.
* Only flip submenu to left when right space is insufficient
