MONITOR: Expose the monitor's services type
    
    Let's expose the monitor's service type so it can be passed by the
    services to the RegisterService method.
    
    It will be needed in the future, for socket-activation of the
    responders, as we will need to differentiate the cases where the
    service being registered is still not in the list of the services but is
    still a valid case because it was just socket-activated.
    
    Related:
    https://fedorahosted.org/sssd/ticket/2243
    
    Signed-off-by: Fabiano Fidêncio <fidencio@redhat.com>
    Reviewed-by: Pavel Březina <pbrezina@redhat.com>
    Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>
    Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>