Possibly merge resolve_definition_of_name_in_module with resolve_name_in_module

[catamorphism]

As per comment in the former function in resolve.

[emberian]

Still relevant

[thestinger]

Triage bump.

[huonw]

Still there.

[ahmedcharles]

I looked into this, it seems less trivial than I imagined, because the functions don't seem to do the same thing or return the same types (or at least, I don't know enough to recognize the similarities).

[tamird]

There's a whole host of duplication in librustc_resolve/lib.rs, but refactoring it would require lots of closure-passing. I'm not really sure it's appropriate to mark as E-easy :(

[nrc]

Fixed by #29530