[clang] [LifetimeSafety] Add details for `-Wlifetime-safety-return-stack-addr` diagnostic (PR #199432)

[Utkarsh Saxena via cfe-commits]

https://github.com/usx95 commented:

Overall looks great. This is a significant improvement to the diagnostic text.

 Some suggestions about code layout.

https://github.com/llvm/llvm-project/pull/199432