[llvm] [LV] Reland "Add costs for VPInstructionWithType::computeCost" (PR #202952)

[Luke Lau via llvm-commits]

lukel97 wrote:

> I'm confused by the build failures. It works downstream. :(

Looks like 054a840e0370704c9a9705f5660861f0364d08d8 landed on main which by coincidence also added the same VPInstructionWithType::computeCost overload, and the CI is testing the merge commit against main!

https://github.com/llvm/llvm-project/pull/202952