virtio_gpu: initial driver

sample for qemu: -device virtio-vga,edid=on,xres=1024,yres=768 -display sdl
display mode can be set in the Screen preferences.

Change-Id: If1d6aeecb208ce7c62c42eea1a95c71237c4375a
Reviewed-on: https://review.haiku-os.org/c/haiku/+/7038
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>