PrivateFieldCouldBeFinalRule support for JPA entities

PrivateFieldCouldBeFinalRule is often not desirable for  fields defined in entity classes. I added new property "ignoreJpaEntities" to aforementioned rule. When the property is set to true, fields inside classes annotated with @Entity or @MappedSuperclass are ignored. 
I observed that PrivateFieldCouldBeFinalRule violations often happen in entity classes (persisted fields in fact should not be final) and at the same time I don't want to disable PrivateFieldCouldBeFinalRule fully. I just want it to be configurable to ignore JPA entities.

I also added new method boolean hasAnyAnnotation(AnnotatedNode node, String... names) to AstUtil.
Everything is tested.