Introduce guest agent specific job categories to allow threads to
run agent monitor specific jobs while normal monitor jobs can
also be running.
Alter _qemuDomainJobObj in order to duplicate certain fields that
will be used for guest agent specific tasks to increase
concurrency and throughput and reduce serialization.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com> Reviewed-by: Jiri Denemark <jdenemar@redhat.com>