[enhancement] Improve ScopedVerifyProcEquivalence for changes to state elements

### What's hard to do? (limit 100 words)

It should be possible to improve ScopedVerifyProcEquivalence to support procs which are transformed by removing or changing the types of state elements. Information about what the transform is expected to have done would need to be carried along in some sort of metadata package.

### Current best alternative workaround (limit 100 words)

Manual verification.

### Your view of the "best case XLS enhancement" (limit 100 words)

Wider equivalence proving usage.