anv: Refactor for allowing multiple queues

We don't really have more than one queue today but it may be a thing in the future. For instance, with preemption, we could allow multiple 3D queues if we wanted to and they would roughly run in parallel. I'm not sure this would be good for app performance but we could do it.

Right now, ANV pretty heavily assumes a single queue. It's not as bad as it was but it's still pretty bad. This series breaks down this assumption and refactors things for arbitrarily many queues. I've not yet written the patch to allow more than one queue as I'm not sure what the perf impact would be or exactly when we'd want to turn it on. However, it should be as simple as dropping a few asserts and changing the advertised value of VkQueueFamilyProperties::queueCount.