[clang] [NFC][LifetimeSafety]: Track assignment history within a single CFGBlock (PR #196075)

[Yuan Suo via cfe-commits]

suoyuan666 wrote:

I have shifted the logic from tracing expressions to tracing Origins.

Currently, I only store the `SrcOrigin`, as it will become the `DestOrigin` of the preceding expression. Since the `DestOrigin` of the final expression is simply the `Origin` corresponding to the misused variable, I believe it might be unnecessary to record it.

please let me know if I missed anything.

https://github.com/llvm/llvm-project/pull/196075