[TASK] Mark properties and methods in ActionController internal

Several properties and methods in the ActionController
are marked interal and will remain as is only until
TYPO3 11 LTS. From version 12.0 on, said properties and
methods may change or vanish without further notice.

Releases: master
Resolves: #92996
Change-Id: Ia03f4746f45dcc9223907c9c8a4927e2e1f86876
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/67008


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Benjamin Franzke <bfr@qbus.de>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benjamin Franzke <bfr@qbus.de>
Reviewed-by: Benni Mack <benni@typo3.org>