Provide examples for using Qt Device Utilities C++ classes and QML types

One of the strengths of Qt is the comprehensive documentation and ready-to-run examples that help developers to learn quickly.

Qt Device Utilites has API documentation (e.g. https://doc.qt.io/QtDeviceUtilities/qtnetworksettings-module.html ) but it should also come with standalone examples so that users can see how to use them.