Merge virtIO and virtIO sound examples together

[Ivan-Velickovic]

At the time of writing, we now have a virtio example that shows of libvmm's support for the virtIO console and block devices. We also have a virtio-snd example that shows off the support for virtIO sound.

Originally, we had planned for these two to be merged into one example when we merge all the work regarding sound.

However, to support block we need a driver VM and we also need a driver VM for audio. This presents a problem as for these driver VMs to initialise and talk to their respective pass-through devices, they need access to certain busses (I believe for things like pinmux/clock).

Giving both of these VMs access to these busses does not work. This is a general issue when having multiple driver VMs and not specific to virtIO but this is the first instance where it is a problem for us.

We are working on native drivers for clock/pinmux and once those are done hopefully we can resolve this issue.