[TASK] Allow icons from Icon Registry in login providers

FontAwesome will be phased out in a short while. As a precursor patch,
login providers are prepared to accept a new option `iconIdentifier`
which takes any icon from the Icon Registry.

To ease the migration for 3rd party extension authors, this patch is
aimed to be backported to v11.

To make the login view itself a bit more logical, the link to reset a
user's password is now moved above the available login providers.

Resolves: #97950
Releases: main, 11.5
Change-Id: I96f6026c6726cf9dbc2635484bc7ad527f70b4d7
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/75191


Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>