Instances could do a better job of identifying if they're satisfying affinity requests or not

[smklein]

See: #7447 (comment)

Currently affinity/anti-affinity rules are used during the "sled reservation" component of VMM starting, but are not subsequently checked.

However, with permissive rules, it's possible that these affinity/anti-affinity requests are violated, and later could be re-inspected.

This issue tracks exposing an API to identify: "Is this instance satisfying affinity rules?"

Related, we could expose an API to identify: "Are there any instances violating affinity rules?"