[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
[FEATURE] Allow escaping of dots in TypoScript key

This patch allows the use of backslashes to escape
dots in TypoScript keys, for example:

my\.escaped\.key = test

will result in a single key "my.escaped.key" with the
value "test".

Resolves: #29461
Releases: 6.2
Change-Id: If830c67c4a35ec023b03f208e1c7131ce57b27b8
[BUGFIX] Correct order of key / field deletion

Prevent a SQL error when deleting a key and the field belonging
to the key in the install tool at the same time.

Therefore the order for deleting keys and fields is changed from
field first and key second to key first and field second.

Resolves: #50450
Releases: 6.2
Change-Id: I30aff6ea6c2bf01dec6197eec8fd3aa7306cfcbb
[BUGFIX] Escape title of of image links

This patch adds a missing call to htmlspecialchars() when
the title tag of image links is initialized.

Resolves: #50760
Releases: 6.2
Change-Id: If41f33d9621f7790c0ff0de4aebcd7cdcb59707f
[BUGFIX] Fix PHP warning when writing to Backend user log

The writelog method for the BackendUserAuthentication object is now
checking if there is actually a uid available in the user array
before it tries to access it.

This prevents a PHP warning about an illegal string offset when writing
log messages in an authentication service.

Releases: 6.0, 6.1, 6.2
Resolves: #49328
Change-Id: I006c6b0ccd8f03292715a7d7ab8e457914637d93