Add domain validators support for TYPO3 10+

[klamparski]

Since TYPO3 10.0 domain validators are not automatically registered anymore (ref). Now every domain validator needs to be registered manually in controller annotations.

t3api validation was relaying on this automatically registered validators. It means it is needed to implement possibility to register validators. To keep consistency with TYPO3 core domain validators, which are registered per controller's action, validators in t3api should be registered per operations.