[clang] [PATCH 1/7] [clang] Improve nested name specifier AST representation (PR #147835)

[Matheus Izvekov via cfe-commits]

mizvekov wrote:

My game plan for merging this PR is to merge all the other PRs into this branch, collapsing everything into a single PR again.
Then wait for CI to pass, and merge it.

Let me know if you have better ideas.

https://github.com/llvm/llvm-project/pull/147835