[llvm] [IR][InstCombine] Add `N{U,S}WAddLike` matchers. (PR #86082)

[via llvm-commits]

goldsteinn wrote:

> Missing fold: https://alive2.llvm.org/ce/z/jZgVSn See also [dtcxzyw/llvm-opt-benchmark#439 (comment)](https://github.com/dtcxzyw/llvm-opt-benchmark/pull/439#discussion_r1533659346)
> 
> https://github.com/llvm/llvm-project/blob/2096f37d7a580a4b4ddce2a44abb80ff90f273ee/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp#L960-L974

I'm sure there are alot of folds missing... this patch was really just about the matcher and a quick replacement of the trivially cases.

https://github.com/llvm/llvm-project/pull/86082