[clang] [clang-tools-extra] [Clang] Unify interface for accessing template arguments as written for class/variable template specializations (PR #81642)

[Erich Keane via cfe-commits]

erichkeane wrote:

> I'd like someone to review the AST matcher changes (the code owner listed in `CodeOwners.rst` appears to be inactive).

Ah, yes!  Unfortunately I think he's the best person to review, I don't know of anyone familiar enough with the matchers.  But he'll be back next week.

https://github.com/llvm/llvm-project/pull/81642