[TASK] Move default salt methods to factory function

To use saltedpasswords in the install tool it is necessary to move the
default salt methods registration from ext_localconf.php to the salt
factory. This patch adds an initialize function to set the default salt
methods.

Resolves: #51404
Releases: 6.2
Change-Id: Iaa4547255c8d6e3b0b0fd75c0aaadfa54109ba27
Reviewed-on: https://review.typo3.org/23369
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters