Tracking issue for `TypingMode` transition

[lcnr]

#131856 transitions the type system from separately tracking the Reveal in the ParamEnv, and intercrate and defining_opaque_types in the InferCtxt to tracking all of that state in a shared enum TypingMode as a field on the InferCtxt.

This is a necessary step towards correctly handling opaque types after type inference, but during analysis. This needs a separate typing mode where we reveal the opaque types defined by that body without accidentally trying to define them. It may also be used to properly support negative reasoning in coherence.

This issue is mostly used to get something to point to in FIXMEs.

• for perf: modify const_eval queries to be named _raw, take a ParamEnv and have wrappers which assert that the typing_mode is PostAnalysis.
• perrrf: intern typing_mode
  • useful for normalizing in writeback causes cycle errors with generators trait-system-refactor-initiative#82 (comment)