[llvm] [LV]: Teach LV to recursively (de)interleave. (PR #89018)

[Mel Chen via llvm-commits]

https://github.com/Mel-Chen approved this pull request.

The IR looks correct.
I temporarily accept this solution, although it will generate Σ(2^i), i = 0 to factor interleave2/deinterleave2. 
Please wait for other reviewers @fhahn @ayalz for a few days.

https://github.com/llvm/llvm-project/pull/89018