[llvm] [AA][MemCpyOpt] Introduce CapturesBeforeAnalysis and ChainedCaptureAnalysis (NFCI) (PR #174739)

[Antonio Frighetto via llvm-commits]

antoniofrighetto wrote:

Okay, I think there's no way we can set `OrAt` to true as EEA intrinsically provides cached (approximate) results. Reworked this by skipping arguments during mod/ref refinement only if the precise analysis let us do so (reflecting callCapturesBefore behavior). Hopefully should be on the correct track now.

https://github.com/llvm/llvm-project/pull/174739