feat(virtq): add packed virtio ring primitives

[andreiltd]

Add low-level packed virtqueue ring implementation in hyperlight_common::virtq, based on the virtio packed ring format.

This is split from: #1368 and does not include any actual plumbing for guest/host communication.

Useful materials:

• HIP: https://github.com/andreiltd/hyperlight/blob/tandr/rng-rfc/proposals/0001-rng-buf/README.md
• spec: https://docs.oasis-open.org/virtio/virtio/v1.3/csd01/virtio-v1.3-csd01.html#x1-720008
• redhat docs: https://www.redhat.com/en/blog/packed-virtqueue-how-reduce-overhead-virtio