[TASK] Fix accessibility issues in topbar and menu

To increase the accessibility of the backend, some issues in the
topbar and menu were fixed.
This patch is one pre-patch to make the accessibility CI test
possible soon.

Resolves: #103284
Releated: #103283
Releases: main, 12.4
Change-Id: I5810c05a9af9f341f6d87584aa620d7979a93f79
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/83217


Reviewed-by: Benjamin Franzke <ben@bnf.dev>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Benjamin Franzke <ben@bnf.dev>