[TASK] Add strict parameter to base64url decode

PHP's base64_decode has a strict parameter to only
accept characters of the corresponding base64 alphabet,
see https://www.php.net/manual/en/function.base64-decode.php

Resolves: #102620
Releases: main, 12.4
Change-Id: I39a038519ec1e884ba42f691c6dea76cbce772fe
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/82139


Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Jörg Bösche <typo3@joergboesche.de>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Stefan Bürk <stefan@buerk.tech>