New API definition: ``port-numa-affinity-policy``. The new field
added to ``ports`` API, ``numa_affinity_policy``, represents the NUMA
affinity policy requested by this port during the virtual machine
scheduling.
Values: "None", "required", "preferred", "legacy".
Change-Id: I5402a8ad462a10c51dc251cb4561b64dbf0b8744
Related-Bug: #1886798