[llvm] [SandboxVec] Implement Pass class (PR #107617)

[Arthur Eubanks via llvm-commits]

https://github.com/aeubanks commented:

didn't notice the first time, but I would have thought this would go in the SandboxVectorizer, not SandboxIR? why are you deciding to put this in SandboxIR?

https://github.com/llvm/llvm-project/pull/107617