Ported commands that are marked 'user_only' will not be considered for
QMP monitor sessions. This allows to implement new commands that do not
(yet) provide a sufficiently stable interface for QMP use.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>