Auto merge of #110031 - compiler-errors:generic-elaboration, r=b-naber

Make elaboration generic over input

Combines all the `elaborate_*` family of functions into just one, which is an iterator over the same type that you pass in (e.g. elaborating `Predicate` gives `Predicate`s, elaborating `Obligation`s gives `Obligation`s, etc.)

Author: bors