[mlir,python] Fix case when `FuncOp.arg_attrs` is not set#117188

makslevental merged 4 commits intollvm:mainllvm/llvm-project:mainfrom

Wheest:Wheest/fix_pyfunc_arg_attrsWheest/llvm-project:Wheest/fix_pyfunc_arg_attrsCopy head branch name to clipboard