[TASK] Make panels context aware

The new panel element styling is context aware and
adapts to light and dark color schemes. The markup
was streamlined, workarounds dropped and now
features improved focus and hover styles.

Resolves: #104818
Resolves: #104798
Releases: main
Change-Id: I9cf2b1c203b8a38c0c0675ff26a08131b0277923
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/85725


Tested-by: Andreas Nedbal <andy@pixelde.su>
Tested-by: Benjamin Franzke <ben@bnf.dev>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Andreas Nedbal <andy@pixelde.su>
Reviewed-by: Benjamin Franzke <ben@bnf.dev>