[clang] [LifetimeSafety] Introduce buildOriginFlowChain for use-after-scope (PR #199345)

[Yuan Suo via cfe-commits]

suoyuan666 wrote:

In fact, the modifications to the test cases are not final yet, as the names for some `Expr *` corresponding to `SrcOrigin` haven't been extracted.

I held off on handling this part because I wasn't entirely sure if the current note format is appropriate.

https://github.com/llvm/llvm-project/pull/199345