[clang] [LifetimeSafety] Introduce buildOriginFlowChain to use-after-invalidation (PR #208891)

[Gábor Horváth via cfe-commits]

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

Overall, looks good to me. I have one nit inline but that could be a separate PR. 

https://github.com/llvm/llvm-project/pull/208891