Allow fluent API to reuse existing named entity graphs

[dnl50]

Hi there,

the fluent API currently only has the ability to dynamically define an entity graph using the FetchableFluentQuery.project methods. It would be nice to be able to reuse existing named entity graphs (e.g. defined through the NamedEntityGraph annotation).

I don't know if this is the right project for the feature request, but since named entity graphs are a JPA feature, I thought this would be the right place.

Best Regards
Daniel