[llvm] [LV] Support strided load with a stride of -1 (PR #128718)

[Mel Chen via llvm-commits]

Mel-Chen wrote:

Changes:
- Remove strided store functionality; will be supported in a future patch.
- Introduce VPWidenStridedLoadRecipe and explicitly pass the stride into the recipe.
Please take a look again, thanks.

https://github.com/llvm/llvm-project/pull/128718