[llvm] [llvm][CodeGen] Add a new software pipeliner 'Window Scheduler' (PR #84443)

[Hua Tian via llvm-commits]

huaatian wrote:

> Okay, we will handle it right away.

I have completed the relevant modifications, but this merge () seems to have issues, causing the code checks to fail on my local machine:(

https://github.com/llvm/llvm-project/pull/84443