Core: Initializing subgroups when AuthzRoles are initialized (method init in AuthzResolverBlImpl)

- before initializing all users roles, prepare also subgroups and add them to the AuthzRoles
- if some Group not exists in the moment of resolving, log this and continue with another Group
- add only those Groups which are not already in the list of IDs
- add test for this funcionality to AuthzResolverIntegrationTest.java