Fix aria.js bugs: incorrect role element problem, mobile focus problem, tippy problem (#23450) (#23486)

Before: the `aria.js` is still buggy in some cases.

After: tested with AppleVoice, Android TalkBack (I tested it with 1.19
again)

* Fix incorrect dropdown init code
* Fix incorrect role element (the menu role should be on the `$menu`
element, but not on the `$focusable`)
* Fix the focus-show-click-hide problem on mobile. Now the language menu
works as expected
* Fix incorrect dropdown template function setting
* Clarify the logic in aria.js
* Fix incorrect tippy `setProps` after `destroy`
* Improve comments
* Implement the layout proposed by #19861

web_src/js/features/repo-legacy.js

@@ -601,9 +601,6 @@ export function initRepository() {
 }
 
 function initRepoIssueCommentEdit() {
-  // Issue/PR Context Menus
-  $('.comment-header-right .context-dropdown').dropdown({action: 'hide'});
-
   // Edit issue or comment content
   $(document).on('click', '.edit-content', onEditContent);