JIT: pgo/devirt diagnostic improvements (#53247)

JIT: pgo/devirt diagnostic improvements (#53247)

Several changes to help better diagnose PGO and devirtualization issues:
* Report the source of the PGO data to the jit
* Report the reason for a devirtualization failure to the jit
* Add checking mode that compares result of devirtualization to class profile
* Add reporting mode to assess overall rates of devirtualization failure
  when the jit has exact type information.

Also fix a loophole where in some case we'd still devirtualize if not
optimizing.

Note crossgen2 does not yet set devirtualization failure reasons.