Get a simplified description of the args_type for a flow.

def _GetArgsDescription(self, args_type):
    """Get a simplified description of the args_type for a flow."""
    args = {}
    if args_type:
      for type_descriptor in args_type.type_infos:
        if not type_descriptor.hidden:
          args[type_descriptor.name] = {
              "description": type_descriptor.description,
              "default": type_descriptor.default,
              "type": "",
          }
          if type_descriptor.type:
            args[type_descriptor.name]["type"] = type_descriptor.type.__name__
    return args