[BUGFIX] Deduplicate slugs with language -1

Checking for duplicate slugs in DataHandler will
now make sure that no two fields with the same
slug exist, where one of them has a language of
-1.

Existing records are not migrated. This could be
done in a followup patch or with a community
extension.

When new records are created or changed which have a
field of type "slug", a unique handling ensures that
no records exists with the same slug (depending
on the additional settings "unique", "uniqueInSite"
and "uniqueInPid").

The language is considered as well: Records with
the same slug can exist if the language differs.

But language -1 was not considered previously.
Since -1 means all language, no other record with
the same slug should exist in ANY language if a
record with language -1 exists.

Resolves: #99529
Releases: main, 11.5
Change-Id: I919c3a3954df02cd55c701c480f6c1a8c87d84d5
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/77407


Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: core-ci <typo3@b13.com>