swift

6c066502 - Add an API to map contextual types from the pack to element environment

Add an API to map contextual types from the pack to element environment I'm not really convinced that the existing implementation here is correct in general; it might work for the type checker's use cases, but I don't think we can rely on not seeing opened element archetypes from other expansions in the type we're processing here. But we can at least tread water while offering a more convenient API.