[llvm] [VPlan] Add initial anlysis to infer scalar type of VPValues. (PR #69013)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

Latest comments should be addressed, thanks!

> Underlying values are used only when we have to, right? Worth emphasizing somewhere.

Yep, I added the info from the patch description to the documentation in VPlanAnalysis.h

https://github.com/llvm/llvm-project/pull/69013