[clang] [LifetimeSafety] Implement a basic use-after-free diagnostic (PR #149731)

[Utkarsh Saxena via cfe-commits]

usx95 wrote:

### Merge activity

* **Aug 18, 11:44 AM UTC**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/149731).


https://github.com/llvm/llvm-project/pull/149731