Improve QtPositioning QML API

QtPositioning provides 3 main features:

• Requesting the position info via QGeoPositionInfoSource.
• Requesting the satellite info via QGeoSatelliteInfoSource.
• Monitoring selected areas using QGeoAreaMonitorInfoSource.

All of those are C++ APIs.

Now when we talk about QML, the situation is much worse. We only have PositionSource QML element that represents QGeoPositionInfoSource.

The scope of this epic is to provide QML APIs for the other two features. This will give us a better support of mobile platforms (at least, Android), because most of the mobile apps use QML for the UI anyway.

There is already a long-pending request from the community to add support for SatelliteInfo in QML (see linked Jira tasks). The main problem here is that not all backends provide this information (the biggest issue is iOS). However in Qt 6 we extended NMEA plugin, so we can use it on all desktop platforms, and the Android plugin also provides the info. So for iOS we can just mention the limitation in the documentation.

As for the area monitoring - our current backend simply uses the QGeoPositionSource provided by the platform, so this should be available on all platforms.