[TASK] Add LoginType enumeration

[TASK] Add LoginType enumeration

A new enumeration class "LoginType" is added to simplify readability and validation
of correct strings within the TYPO3 Authentication process.

Resolves: #85402
Releases: master
Change-Id: Ib53ed304de5662f5bd8628509a229b2832ff18fa
Reviewed-on: https://review.typo3.org/57390
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Henning Liebe <h.liebe@neusta.de>
Tested-by: Henning Liebe <h.liebe@neusta.de>
Reviewed-by: Sascha Rademacher <sascha.rademacher+typo3@gmail.com>
Tested-by: Sascha Rademacher <sascha.rademacher+typo3@gmail.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>