Hook NUMA topology checking into claims

This patch adds the ability to test claims against NUMA topology exposed
by the host and instance. This is currently a no-op as no code in the
scheduler will actually attempt to set the limits against numa_topology.
Since getting the NUMA topology of the instance may require an additional
db roundtrip, we try to avoid getting it unless absolutely necessary.

This patch also changes the resource_tracker resize_claim method to
accept the image_metada of the instance as it is used (alongside flavor)
to calculate the new topology that will be exposed after the resize is
done.

The resource tracker will not do any actual usage tracking yet - this
will be done in a follow-up patch.

Blueprint: virt-driver-numa-placement
Change-Id: I07b690243d481c855c5e706f968cf224b336a1a0
Merge "Hook NUMA topology checking into claims"