[llvm] [APInt] Implement average functions without sign/zero-extension. NFC. (PR #85212)

[Atousa Duprat via llvm-commits]

Atousa wrote:

> > * @Atousa (for some reason I cannot add you as a reviewer).
> 
> Only people with commit access can be tagged as a reviewer (and can accept PRs) - but comments on the patch are still encouraged

@RKSimon Not sure if I have commit access or not yet?

https://github.com/llvm/llvm-project/pull/85212