[llvm] [LV] Support scalable interleave groups for factors 3, 5, 6 and 7 (PR #141865)

[Ramkumar Ramachandra via llvm-commits]

https://github.com/artagnon approved this pull request.

This patch looks good to me, considering that we will strip factors > 8 in a follow-up. I will however defer to @fhahn to decide whether to still lower to VPIntrinsics in the VPlan.

https://github.com/llvm/llvm-project/pull/141865