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:core
- EXT:extensionmanager
- EXT:install

All @api annotations have been removed.

Resolves: #86517
Releases: master
Change-Id: I7869d8e3b6e8a4365529cc7c98b99cde7ca1495f
Reviewed-on: https://review.typo3.org/58532


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