[FEATURE] Custom active tab in RTE element browser

Introduce a flag that prevents the element browser of rtehtmlarea
from overwriting the active tab that was set by a hook object.

Resolves: #49036
Releases: 6.2
Change-Id: Iebfda39714caa98c0d2023992bbf63a2f5b9b01a
[TASK] Non extension dirs in llXmlAutoFilename

Allow non extension dirs (e.g. fileadmin) in
\TYPO3\CMS\Core\Utility\GeneralUtility::llXmlAutoFilename()

Fixes: #34728
Releases: 6.2, 6.1, 4.7, 4.5
Change-Id: I073f42ec8b6d733246151df331201031187e1baf