[llvm] [mlir] Add llvm::min/max_element and use it in llvm/ and mlir/ directories. (PR #84678)

[Justin Lebar via llvm-commits]

jlebar wrote:

I mean clearly this is not going to build, https://github.com/llvm/llvm-project/pull/84678/files#diff-0dbd9d956d4dcee3f73f026710249c7ccf6a131aa98a384f0fa2da1670174368R1073

https://github.com/llvm/llvm-project/pull/84678