Implement lock owner support

[beikov]

We already have an annotation for defining a lock owner mapping but currently there is no implementation for this. A lock owner is an entity that should be used for locking.
This allows to define that an update on a child should use a lock on a parent. Maybe we should even consider allowing multiple lock owners?
This is different to the LockMode.AUTO which when defined for a child that is a child instance of a parent updatable entity view, will inherit the parent as lock owner. It should also be possible to disable the inheriting of the parent as lock owner.