[clang] [clang] Instantiate attributes on other decl types (PR #115924)

[Erich Keane via cfe-commits]

https://github.com/erichkeane commented:

Still need tests for namespacealiasdecl, typedefnamedecl, and typealiastemplatedecl actually being instantiated.

Also, is there a reason why the only way to currently test these are with the plugins?  I would expect there to be SOME builtin attribute that could be validated for all of those as well.

https://github.com/llvm/llvm-project/pull/115924