vpda suspend, detach and hotplug live migrate

bug https://bugs.launchpad.net/nova/+bug/1970467 tracks removign the api blocks for operations with vdpa ports that currently work in the code now that they have been tested with real hardware.
(cold migration, resize, shelve and evacuate)

This blueprint proposes completing the feature set by adding support for interface detach, suspend and hotplug live migrations.

detach currently does not work because we do not parse the source device path form the dev attribute of the source element in the libvirt XML.
https://review.opendev.org/c/openstack/nova/+/841016

suspend does not work because of how suspend currently detaches the vifs
https://review.opendev.org/c/openstack/nova/+/841017

and hotplug live migration simple need vdpa to be added to the list of passthoug devices that need to be detached https://review.opendev.org/c/openstack/nova/+/841012

with these 3 small changes we can have feature parity with neutron sriov direct mode interfaces and enable all VM lifecycle operations.

transparent vdpa live migration is out of scope of this blueprint as that requires additional feature development in qemu and the kernel.