Allow passing in an entity graph on EntityManager.refresh

[trajano]

At present I do the following to reload an entity such that all the fields in the entity graph provided are loaded

    entityManager.detach(entity);
    final var entityType = entityManager.getMetamodel().entity(entity.getClass());
    final var entityGraph = entityManager.getEntityGraph(entityType.getName());
    return (T)
        entityManager.find(
            entity.getClass(),
            entity.getId(),
            Map.of(
                "jakarta.persistence.loadgraph", // or "jakarta.persistence.fetchgraph"
                entityGraph,
                "jakarta.persistence.cache_retrieve_mode",
                CacheRetrieveMode.BYPASS));

It would be cleaner I think if I can simply do

    final var entityType = entityManager.getMetamodel().entity(entity.getClass());
    final var entityGraph = entityManager.getEntityGraph(entityType.getName());
    entityManager.refresh(entity, 
            Map.of(
                "jakarta.persistence.loadgraph", // or "jakarta.persistence.fetchgraph"
                entityGraph));
   // and no cache retrieve mode

To reload the entity with the graph that was provided.

[gavinking]

This would be useful, and will be easier to in light of the direction we've decided to take #383.

[gavinking]

See #672

[gavinking]

I am moving this one off the road map for 4.0. We have a lot on our plate and:

1. this one imposes an implementation burden and,
2. risk, since we do not have a prototype implementation anywhere yet.