[clang] [Clang][UnsafeBufferUsage] Warn about two-arg string_view constructors. (PR #180471)

[Nico Weber via cfe-commits]

nico wrote:

Sorry for the slow report, but this makes clang assert on this input: 
[ir_to_program-98a532.zip](https://github.com/user-attachments/files/25877767/ir_to_program-98a532.zip)

```
 % ./ir_to_program-98a532.sh 2>&1 | head -1
Assertion failed: (Name.isIdentifier() && "Name is not a simple identifier"), function getName, file Decl.h, line 302.
```

https://github.com/llvm/llvm-project/pull/180471