bugfix: fix tdnr + name resolution bug

[mitchellwrosen]

Overview

Fixes #5369

This PR fixes the bug demonstrated in #5369. As of this PR, name resolution (logically) works as follows:

• When resolving a name foo,
  • Start with all names in scope (the project local definitions, direct dependencies, and indirect dependencies)
  • Throw away names that don't end in foo
  • Throw away indirect dependencies, unless they're all indirect dependencies
  • This implements the "prefer direct deps to indirect deps" logic
  • (for terms only) Throw away names that don't typecheck (i.e. do TDNR)

Previously, the last step did not properly shadow namespace names with file names, and furthermore was a little out of sync with the "prefer direct deps" rule.

Test coverage

I've added a regression test for #5369, and another big transcript that shows how TDNR works in a number of different situations

[aryairani]

I'm going to merge anyway to help with dogfooding, but we can still tweak the transcripts.