OGM-548 Remove redundant properties from relationships in Neo4j

https://hibernate.atlassian.net/browse/OGM-548

This pull requests will remove the TEMP nodes, the redundant properties on the relationship for associations and collection of embedded.

I had to add some values on the AssociationKey and the AssociationContext to achieve this.

Note that it won't affect the additional properties on OneToOne and it won't create a separtate node for an embedded attribute (There are separate issuesfor this).
> I've also added the field AssociationKey#targetKey but writing this reply I've noticed that I can remove it.

Yes, having target key on `Association` seems not to make so much sense as there can be several rows in an association. But I feel in `RowKey` it may fly?