Implement the VmsService

[JeroenSoeters]

We need a way to manage virtual machines in Aurae. The PodSandbox work can be layered on top of this: #433

[JeroenSoeters]

With a few small changes (#447) auraed is now running as true PID 1 in a VM spawned with cloud-hypervisor. The VM uses a custom kernel with PVH enabled so we can do a direct kernel boot instead of a full firmware boot. For this kernel I've borrowed cloud-hypervisor's config but with IPv6 enabled. We should review those kernel options. The binaries are being copied onto the disk image now after every build.

There are a few open questions for which we already have other issues:

• what will the networking set up look like: TAP devices and virtio sock for guest auraed #446
• how do we go about certificate provisioning: Strategy for TLS certs/keys in recursive Aurae daemon #328

Another big open question is how will we deploy the hypervisor(s) and which one(s) do we support.

[JeroenSoeters]

Apparently we had an open issue for the kernel discussion as well :)

#238