65571: REST changes to delete of an item

- fix RelationshipDeleteRestRepositoryIT test failures
    - fix issue with deleting a collection with ResourcePolicies
- remove a redundant itemService from ItemRestRepository
- implement input validation on the copyVirtualMetadata parameter
    - add test for this
- use Object.deepEquals() for array comparison
- documented deleteMultipleRelationshipsCopyVirtualMetadata()

dspace-api/src/main/java/org/dspace/content/CollectionServiceImpl.java

@@ -761,6 +761,8 @@ public class CollectionServiceImpl extends DSpaceObjectServiceImpl<Collection> i
         // Remove any workflow roles
         collectionRoleService.deleteByCollection(context, collection);
 
+        collection.getResourcePolicies().clear();
+
         // Remove default administrators group
         Group g = collection.getAdministrators();