IFP: Resolve group names from GIDs if required
    
    The AD provider only converts SIDs to GIDs during initgroups
    to improve performance. But this is not sufficient for the
    org.freedesktop.sssd.infopipe.GetUserGroups method, which needs to return
    names.
    
    We need to resolve the GIDs to names ourselves in that method.
    
    Resolves:
    https://pagure.io/SSSD/sssd/issue/3392
    
    Reviewed-by: Pavel Březina <pbrezina@redhat.com>
    (cherry picked from commit 95acbbb3fbfe972fecd3d8dcbc40d6b1d6b1d354)