[llvm] [RISCV] Emit VP strided loads/stores in RISCVGatherScatterLowering (PR #98111)

[Luke Lau via llvm-commits]

lukel97 wrote:

> It looks like all the mentioned changes have landed, is this ready for a rebase?

https://github.com/llvm/llvm-project/pull/98140 was reverted due to the tests getting out sync, once that's relanded though this should be good to go.

https://github.com/llvm/llvm-project/pull/98111