conf: add VIR_DOMAIN_VIDEO_TYPE_PARALLELS video type

conf: add VIR_DOMAIN_VIDEO_TYPE_PARALLELS video type

We support VNC for containers to have the same
interface with VMs. At this moment it just renders
linux text console.

Of course we don't pass any physical devices and
don't emulate virtual devices. Our VNC server
renders text from terminal master and sends
input events from VNC client to terminal.

So add special video type VIR_DOMAIN_VIDEO_TYPE_PARALLELS
for these pseudo-devices.

Signed-off-by: Dmitry Guryanov <dguryanov@parallels.com>