[llvm] [VPlan] Move call widening decision to VPlan. (NFCI) (PR #195518)

[Andrei Elovikov via llvm-commits]

https://github.com/eas commented:

Even though this is NFC, I think pre-committing a test(s) with a VPlan dump after mem widening decisions and updating it to dump after this pass would be beneficial. It would become even more useful when we switch off the old CM code path as it would become a single source of truth/reasoning about this pass behavior.

https://github.com/llvm/llvm-project/pull/195518