* Revert "Revert "A11Y: Switch tabs using the keyboard (#12241)" (#12260)"
This reverts commit 4c1e02d412.
* FIX: Make sure that the "menu-link" is present when a plugin adds a tab.
Other changes:
- We put the notification tab first using JS instead of CSS. It's important because of the tab number data attribute, which the keyboard navigation uses.
- We only set the button id from the attrs object if it's a tab. Otherwise, it conflicts with the topic footer button