[clang] [LifetimeSafety] Track origins through array subscript and array-to-pointer decay (PR #186902)

[Gábor Horváth via cfe-commits]

https://github.com/Xazax-hun approved this pull request.

Overall, looks good to me, one nit inline. 

https://github.com/llvm/llvm-project/pull/186902