[clang] [clang-tools-extra] Handle recording inheritance for templates (PR #177273)

[Nathan Ridge via cfe-commits]

HighCommander4 wrote:

> I have thought for a long time and I am honestly not quite sure what the problem in your comment [here](https://github.com/llvm/llvm-project/pull/177273#discussion_r2753063230) is and I think I need some elaboration. This is also why there is still no TODO since I am unsure what to write. Like should a `findReference` search on `T` of `T field` return `A`, `B` and `C`?

The other way around: find-references on `A` should turn up `T` in `T field` as one of the found references, since the class has an instantiation in which `T` is substituted for a type that references `A`.

https://github.com/llvm/llvm-project/pull/177273