Augment refcount audit in kerneldump to include kernel objects

[FUDCo]

What is the Problem Being Solved?

Back when we were working on kernel promise retirement we added a feature to the kerneldump utility to run a comprehensive audit of the kernel promise reference counts to verify that we doing them correctly and help diagnose problems when we weren't. Since then, we've added sophisticated inter-vat garbage collection logic which adds reference counts to kernel objects in addition to refcounting promises. The kerneldump refcount audit mechanism should be extended to encompass those, for all the same reasons that feature was added in the first place.

Description of the Design

Promise refcounts are single counts whereas object refcounts are pairs (reachable + recognizable), but otherwise the logic is the same. The current utility looks at all the places that references can live and adds them up. Just so.