libvirt: add daemon itself as shutdown reason

This patch introduces a new shutdown reason "daemon" in order
to indicate that the daemon needed to force shutdown the domain
as the best course of action to take at the moment.

This action would occur during reconnection when processing
encounters an error once the monitor reconnection is successful.

Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy@virtuozzo.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>
Reviewed-by: Erik Skultety <eskultet@redhat.com>