[llvm] Reland: [LV]: Teach LV to recursively (de)interleave. (PR #122989)

[David Sherwood via llvm-commits]

https://github.com/david-arm approved this pull request.

LGTM! This patch is identical to #89018, since the reason for reverting last time was due to a bug in a different IR pass that this PR was exposing. I'm accepting this on the basis that it's identical to before and it has already been thoroughly reviewed and accepted by several reviewers.

https://github.com/llvm/llvm-project/pull/122989