qemu: move detection whether to use -no-reboot to qemu_domain
    
    This will be used later on in implementation of new API
    virDomainSetLifecycleAction().  In order to use it, we need to store
    the value in status XML to not lose the information if libvirtd is
    restarted.
    
    If some guest was started by old libvirt where it was not possible
    to change the lifecycle action for running guest, we can safely
    detect it based on the current actions from the status XML.
    
    Reviewed-by: John Ferlan <jferlan@redhat.com>
    Signed-off-by: Pavel Hrdina <phrdina@redhat.com>