[mlir][arith] Add subui_extended op (#197376) Unsigned extended subtraction mirroring addui_extended. Gives a primitive for unsigned underflow that maps cleanly to llvm.usub.with.overflow and spirv.ISub GitOrigin-RevId: 8edba1a3128ed3c6ab104470ef3f3567bf73c516
See https://mlir.llvm.org/ for more information.