[llvm] Recommit "[CodeGenPrepare] Folding `urem` with loop invariant value" (PR #104877)

[via llvm-commits]

goldsteinn wrote:

> LGTM, but I think the new tests should go into the IR test file, not the asm test file...

Okay, Ill copy tests to IR file before pushing.

https://github.com/llvm/llvm-project/pull/104877