[clang] Adds a pseudonym to clang"s windows mangler... (PR #97792)

[Andrey Ali Khan Bolshakov via cfe-commits]

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bolshakov-a wrote:

I'd prefer something simpler like:
```cpp
struct A { int* pi; };
template <A> void TplFn();
int i;
void Fn() {
  TplFn<A{&i + 1}>();
}
```
with checking of the full mangled name.

https://github.com/llvm/llvm-project/pull/97792