Method when `SearchAsync` is ended with no response?

[Adrian Preuß]

DeviceAvailable calls only when devices found when using SearchAsync.

Serves RSSDP here a method, when the search is ended with no results, for sample:

 deviceLocator.DeviceAvailable       += OnDeviceResponse;
deviceLocator?.SearchAsync(delegate() {
// When search has ended & no results found
});

// [...]
private async static void OnDeviceResponse(object? sender, DeviceAvailableEventArgs e) {
// Devices Found
}