Major update of the LDAP extension for TYPO3!

This release brings official support for TYPO3 v12 and v13 LTS while retaining support for TYPO3 v11, now in ELTS mode. This ensures a smooth upgrade path, as we always strive to provide.

Former signal/slot mechanism has been migrated to PSR-14 events. The import scheduler task is now a Symfony command; so be sure to run the upgrade wizard after upgrading to version 4.0.