[!!!][TASK] Remove sysext:sv, move files to sysext:core

Only the AuthenticationService and its abstract class are
left in sysext:sv. Move those, the tests and the service
registration over to sysext:core.

All mentions of sysext:sv are hereby removed from the core.

Change-Id: I699ace33a7d5a0e7ddff4d3c9ed4e595e40677af
Resolves: #81735
Releases: master
Reviewed-on: https://review.typo3.org/53351


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>