[llvm] [llvm][ctx_profile] Add the `llvm.instrprof.callsite` intrinsic (PR #89939)

[Mircea Trofin via llvm-commits]

mtrofin wrote:

> Can you also update the docs?
> 
> https://github.com/llvm/llvm-project/blob/7c0da7993ecfffe1396a15383eb357fa624265af/llvm/docs/LangRef.rst#L14142-L14143

done. I'll also update the docs again once the ctx lowering pass is in, because the other intrinsics' docs are too specific. The doc for this one can become more precise at that point, too.

https://github.com/llvm/llvm-project/pull/89939