[llvm] [Codegen, X86] Add prefetch insertion based on Propeller profile (PR #166324)

[Rahman Lavaee via llvm-commits]

rlavaee wrote:

> LGTM.
> 
> It would be nice to add a NewPM port of `InsertCodePrefetch`, but given that pass already exists, we can just do that in a future PR when it comes up.

Is this still relevant given that the pass is now arch-independent (defined in Codegen/)?

https://github.com/llvm/llvm-project/pull/166324