IdM Server: list all Employees with matching Smart Card
    
    Implement a new IPA command allowing to retrieve the list of users matching
    the provided certificate.
    The command is using SSSD Dbus interface, thus including users from IPA
    domain and from trusted domains. This requires sssd-dbus package to be
    installed on IPA server.
    
    https://fedorahosted.org/freeipa/ticket/6646
    
    Reviewed-By: David Kupka <dkupka@redhat.com>
    Reviewed-By: Jan Cholasta <jcholast@redhat.com>