Adding support for Entity Type as Id of another Entity

[ismaelgcosta]

When I try to use an Entity as Id of another Entity I got "java.lang.ClassCastException: org.javers.core.metamodel.type.EntityType cannot be cast to org.javers.core.metamodel.type.PrimitiveOrValueType".

I created a PR for this.

Thank you.

[bartoszwalacik]

released in 3.8.3