argAddFileOut function
Implementation
void argAddFileOut(
  ArgParser argParser, {
  required bool isDocument,
}) {
  argParser.addSeparator('IO settings');
  argParser.addOption(
    argNameOut,
    abbr: 'o',
    valueHelp: 'downloaded_${_resourceType(isDocument)}.json',
    help: 'Path of the output file where the ${_resourceType(isDocument)} '
        'JSON will be written. If omitted, STDOUT will be used.',
  );
}