Figure out a way to do name resolution in value vs type namespace #1123
Description
See the discussion at #1101 (comment): we'd like variants of resolve_path that specifically check the value or type namespace.
To my surprise, according to what @oli-obk said, this is actually not entirely trivial to do? Given that this is the basis of name resolution in rustc, I would have expected that to be much simpler than getting a weird "lookup in whatever namespace", which seems to be the operation we have right now.