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

[Erich Keane via cfe-commits]

erichkeane wrote:

> Given how late in the cycle it is, I would say we shouldn't backport _now_ but if we do another point release of 19.x, then we should backport then.

Offline, Aaron and I discussed the changes this release cycle, and I think I agree with this.  We're too close to the current release, but as soon as the gates are open for the next point-release, I'd be fine with this.

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