[BUGFIX] Prefix all CSS for admin panel

Resolves: #72091
Releases: master
Change-Id: I2666cbc431a6c3a9bda6640fd8f123fd58d86ba4
Reviewed-on: https://review.typo3.org/45173


Reviewed-by: Josef Glatz <josef.glatz@typo3.org>
Tested-by: Josef Glatz <josef.glatz@typo3.org>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>