[TASK] Improve DataHandler copy/localize hooks

[derhansen]

With TYPO3 v13, most TCA used in core DataHandler is readonly. Therefore the previously used "hack" to prevent event registrations from being copied or localized does not work any more (see #1289).

As a temporary solution, the new field temp_event_uid has been added to tx_sfeventmgt_domain_model_registration table, so non-deleted registrations will be marked as deleted before copy/localize and the updateis reverted after the copy/localize process is finished.

The new solution is however even more "hacky" than the previous one. It would be good, if TYPO3 core would allow extension developers to define $excludeFields used in DataHandler->copyRecord function.