[clang] [Clang][Parser] Build up QualifiedTemplateName for typo correction (PR #108148)

[Erich Keane via cfe-commits]

https://github.com/erichkeane approved this pull request.

I think this change is sensible/innocuous enough.  While the clangd justification is somewhat motivating, it would depend on where we want to backport it to.

it seems to me that a x.0.0 release would probably be acceptable for backporting, anything else I'd probably not be willing over a crash-on-invalid.

https://github.com/llvm/llvm-project/pull/108148