[TASK] Add proper comments to PHP code

There are some places where PHP comments have been done wrong (using doccomments)
or where there is no comment at all.

Resolves: #80503
Releases: master
Change-Id: Ib12d3b82755d801abcbefe7127f1189239f766af
Reviewed-on: https://review.typo3.org/52200


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Frank Naegler <frank.naegler@typo3.org>
Tested-by: Frank Naegler <frank.naegler@typo3.org>