[llvm] [Transforms][Utils] Add LoopSplitUtils for iteration-space loop splitting (PR #205995)

[Ramkumar Ramachandra via llvm-commits]

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

LGTM, thanks for all the work! I think it's good enough for the tree now, and any improvements can be made in-tree.

https://github.com/llvm/llvm-project/pull/205995