Extract path lock mechanism from publishing modules into core

Due to migrating away from JCR Locks in publication, a concurrency issue was revealed where auto generated content might under some circumstances conflict with content being imported during publication process.

Since we made path locks in publishing JCR-agonostic, the PathLockManager does not know that there's content being autogenerated, and so it allows publication module to import the content even though there's JCR lock in place.

This improvements aims for extraction of path locks from publishing module into core, so that it is possible to replace JCR locks and prevent concurrency issues when modifying same content.