* Support TYPO3 v12.0
All dependencies are compatible now.
We can update to support v12.0.
This commit will shift TYPO3 support from 10 and 11 to 11 and 12.
See Changelog entry.
Update dev dependencies to our latest best practice.
Auto migrate code base to follow CGL and use PHP 7.4.
PHPStan was released with first stable public version 1.x.
The version is updated together with extensions.
The new version finds new issues which are solved right away to not
break CI.
Pages can not be copied by administrators as DataHandler will copy all
pages, including tx_tracking_* tables.
Those are not allowed on tables which will result in error messages.
A test is added to simulate the action and ensure it doesn't fail with
errors.
Results: #52
