[TASK] Doctrine: Migrate BackendUserController

Migrate switchUser and terminateSession to doctrine.

Resolves: #77258
Releases: master
Change-Id: Ia9b62d6057f3fe05224074e73a6d5d64f926f605
Reviewed-on: https://review.typo3.org/49207


Tested-by: Bamboo TYPO3com <info@typo3.com>
Reviewed-by: Mathias Schreiber <mathias.schreiber@wmdb.de>
Tested-by: Mathias Schreiber <mathias.schreiber@wmdb.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>