getDeviceManager method
Get a device management module for managing audio and video related devices such as cameras, microphones, and speakers
Platform not supported:
- web
Implementation
TXDeviceManager getDeviceManager() {
  if (_txDeviceManager == null) {
    _cloudChannel!.invokeMethod('getDeviceManager');
    _txDeviceManager = new TXDeviceManager(_cloudChannel!);
  }
  return _txDeviceManager!;
}