requestNotificationPermissionLinux method

Implementation

@override
Future<String> requestNotificationPermissionLinux() async {
  try {
    final result = await methodChannel.invokeMethod(
      'requestNotificationPermissionLinux',
    );
    return result ?? 'denied';
  } on PlatformException catch (e) {
    debugPrint(
      'Error requesting Linux notification permission: ${e.message}',
    );
    return 'denied';
  }
}