[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] Ignore case in file extension filter

This patch makes the FileExtensionFilter case insensitive.

If the filter is configured to allow files with the ".EXT"
extension it will now also allow files with an ".ext"
extension.

Resolves: #50568
Releases: 6.2, 6.1, 6.0
Change-Id: I5761ab7f06116ef847caeb2ae786e580730c0e6b