[clang] [clang] Diagnose dangling issues for the "Container<GSLPointer>" case. (PR #107213)

[Haojian Wu via cfe-commits]

hokein wrote:

After further testing, this change introduces a new false positive -- we emit a return-stack-address warning for the following case, this is not correct.

```
std::vector<std::string_view> kk() {
  std::vector<std::string_view> s;
  return s;
}
```

Looking now.

https://github.com/llvm/llvm-project/pull/107213