TYPO3 Core

DataHandler has a lot of hidden complexity in huge methods that nobody can fully grasp. Several aspects can be improved to make the class easier to handle, including:

1. introduce early returns in methods/early continues in foreach loops, where possible
2. split up long methods into smaller methods
3. introduce parameter objects to get rid of overly long method signatures

All cleanups should keep the external interface intact for now, deprecation is allowed though.

See #67336 for one of the issues already created for this epic.