intg: Add test for user and group local overrides
    
    Introduce a new integration test for local view overrides.
    
    Regression tests for: #2790, #2757 and #2802.
    
    Resolves:
    https://fedorahosted.org/sssd/ticket/2732
    
    Reviewed-by: Nikolai Kondrashov <Nikolai.Kondrashov@redhat.com>
    (based on commit 8d1dcb6af723f2968410c4b088d06d63d02b4fea)
    (based on commit fed2fdded1060d24bd721fe3fe16034567a7e284)
    (based on commit 3569ade3eaf9bf13c522d228019da228de55398a)