Add group membership management
    
    A group membership manager is a user or a group that can add members to
    a group or remove members from a group or host group.
    
    Fixes: https://pagure.io/freeipa/issue/8114
    Signed-off-by: Christian Heimes <cheimes@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Simo Sorce <ssorce@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>