Introduce a feature bit to force indirect descriptor tables allocation on dedicated pages.

[bafsa-harman]

This new feature bit instructs the driver to allocate every indirect descriptor table on its own dedicated memory pages (i.e. a single memory page must only hold data for exactly one indirect descriptor).

A patch for the specification introducing this new feature was proposed here:

https://lists.oasis-open.org/archives/virtio-comment/202210/msg00002.html

Although this feature is likely to increase memory consumption, it is particularly useful to support a memory protection scheme where both the host and guest address spaces are isolated and virtio buffers are granted dynamically to the host as they are exchanged through the virtqueues.

This approach was presented and discussed on the virtio mailing list here:

https://lists.oasis-open.org/archives/virtio-dev/202207/msg00012.html
https://lists.oasis-open.org/archives/virtio-dev/202209/msg00065.html