Test QtPositioning on all supported platforms

QtPositioning uses plugins system to provide its features under different platforms.

The scope of this task is to test that those plugins work as expected on all supported platforms.

Below is the list of platforms together with the plugins that need to be tested on each of them.

Linux

• [works] positionpoll
• geoclue - tested on Ubuntu 18.04 virtual machine. The plugin starts, connects to Geoclue.Master D-Bus service, but after that fails to get any position provider. Not possible to find any reasonable documentation about how Geoclue is supposed to be working (google brings up only geoclue2 topics).
• [works] geoclue2
• [works] gypsy - works with https://codereview.qt-project.org/c/qt/qtlocation/+/338155
• [works] nmea: serial port, socket and file.

MacOS & iOS

• positionpoll
• corelocation
• nmea (I guess MacOS only): serial port, socket and file.

Windows

• positionpoll
• winrt
• nmea: serial port, socket and file.

Android

• [works] positionpoll
• [works] android

This list is based on https://code.qt.io/cgit/qt/qtlocation.git/tree/src/plugins/position/CMakeLists.txt

Some comments:

• To test positionpoll plugin it might be enough to run tst_QGeoAreaMonitorSource test, which just reads the position data from nmealog.txt file. The test checks all the typical usecases for the plugin.
• NMEA: PositionInfo can be tested from QML (PositionSource object) or C++ (QGeoPositionInfoSource::createSource); SatelliteInfo can be tested from C++ only (QGeoSatelliteInfoSource::createSource).