[llvm] [LV][NFC] Print VPlan's transformation pipline (PR #72665)

[Florian Hahn via llvm-commits]

fhahn wrote:

> I do agree that that is good simple approach. On the other hand to do some baby step towards to pass/passmanager for vectorizer might be useful. The last commit introduces simple base class for pass, wraps all existing xforms and copies existing logic of print-before/after* options. If that looks to much, I'm fine to go with much simpler option

Thanks for the update! I think to start with a simpler option would be preferred.

https://github.com/llvm/llvm-project/pull/72665