[TASK] Salted Passwords: Add a ComposedSaltInterface

Add another interface, in order to allow to code
against interface instead of abstractions,
so composed salts that implement their own
password-hashing can implement this interface.

Relates: #79795
Relates: #79889
Resolves: #83294
Releases: master
Change-Id: Ica97f695b5f005e7b835078e89d17f8003141b3f
Reviewed-on: https://review.typo3.org/55060


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Nicole Cordes <typo3@cordes.co>
Tested-by: Nicole Cordes <typo3@cordes.co>
Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Tested-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>