ci: add virtio-snd building

[Ivan-Velickovic]

No description provided.

[alexandermbrown]

I was thinking we could automatically test virtio-snd by doing the following (I can make a PR later):

1. Run it with QEMU_SND_BACKEND=wav - this allows simulation of audio by saving it to a WAV file
2. In client, login and run aplay /usr/share/sounds/alsa/Front_*
3. Expect the following output after waiting around 5 seconds:

Playing WAVE '/usr/share/sounds/alsa/Front_Center.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Mono
Playing WAVE '/usr/share/sounds/alsa/Front_Left.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Mono
Playing WAVE '/usr/share/sounds/alsa/Front_Right.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Mono

Only issue, sometimes the VM will randomly print [ 55.728546] random: fast init done