[llvm] VPlan: factor out VPUtils into its own file (NFC) (PR #105857)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

Thanks for splitting this off. Was also suggested here https://github.com/llvm/llvm-project/pull/94464#discussion_r1685714902

https://github.com/llvm/llvm-project/pull/105857