[TASK] Mark various parts with phpdoc internal - part 2

All specific controllers for specific Backend actions, Backend-module related modules,
all hook implementations (where the core uses hooks by itself), and module-specific
ViewHelpers are now marked as @internal to ensure developers what is
part of the public TYPO3 Core API.

within
- EXT:seo
- EXT:setup
- EXT:rte_ckeditor
- EXT:workspaces
- EXT:viewpage
- EXT:tstemplate
- EXT:taskcenter
- EXT:t3editor
- EXT:sys_action
- EXT:sys_note

All leftover @api methods have been removed.

Resolves: #86509
Releases: master
Change-Id: I6e5ee2302055de9ea4c124ca913e4677d62721fe
Reviewed-on: https://review.typo3.org/58529


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>