[llvm] [VPlan] Migrate convertToStridedAccesses to VPSCEVExpander (PR #208939)

[Luke Lau via llvm-commits]

lukel97 wrote:

There's a regression in `build.rva23u64-O3-base/MultiSource/Applications/oggenc/CMakeFiles/oggenc.dir/oggenc.s` where we're no longer converting to a strided access, could be a case that `tryToExpand` fails. Can you try creating a reproducer for that?

https://github.com/llvm/llvm-project/pull/208939