[TASK] Enable PHP 8.0 linting and phpstan in CI

Resolves: #93604
Releases: master
Change-Id: I36133bd50c85f572ea0dc9ba786c7ac6e1718adb
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/68146


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Simon Gilli <typo3@gilbertsoft.org>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Richard Haeser <richard@richardhaeser.com>
Reviewed-by: Simon Gilli <typo3@gilbertsoft.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>