Add rate-limiting / io-throttling support
We're using virtio-fs in our multi-tenant CI/CD and quite frequently see noisy neighbor problems that can really impact user impression of our solution. We've recently switched to cloud-hypervisor which is using the fire-cracker rate-limiter module for virtio-block and virtio-net. We're asking if the same support could be offered with virtio-fs so that we could have consistent support and similar isolation guarantees.