[llvm] [KnownBits] Add reduceUMin/reduceUMax support (PR #211310)

[Simon Pilgrim via llvm-commits]

RKSimon wrote:

@MohamedAbdullahi14 Avoid using rebase unless you have no other option as it can affect review comments - just merge, PRs get squashed anyway when they are committed to trunk

https://github.com/llvm/llvm-project/pull/211310