HHH-2781 Test caching of non-updatable state

[beikov]

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https://hibernate.atlassian.net/browse/HHH-2781

[beikov]

The problem is that we use the entity state as it is in org.hibernate.action.internal.EntityUpdateAction#updateCacheItem, whereas we should be using the previous state for non-updatable column values, which might not be so simple if the non-updatable column is part of e.g. an embeddable and another field of that embeddable is dirty.

A possible solution might be to pass the loadedState into org.hibernate.persister.entity.EntityPersister#buildCacheEntry and implement the assembling/disassembling that is currently implemented through org.hibernate.type.Type via ModelPart instead and try to respect updatability in that new implementation, using the loadedState if needed.