Sends a raw ZPL command string directly to the printer.
Example: '^XA^FO50,50^A0N,50,50^FDHello^FS^XZ'
'^XA^FO50,50^A0N,50,50^FDHello^FS^XZ'
Future<String?> sendZPLCommand(String zplCommand) { return _repository.sendZPLCommand(zplCommand); }