Add Google Mobile Services support in QtPositioning android plugin

Apparently positioning performance on android are sub-par.
Using GMS might help.

An attempt has been initiated here:
https://github.com/qt/qtlocation/compare/dev...vok1980:feature/google-play-services-positioning-plugin

At the time of writing, though, the implementation is missing.

Starting point is
https://developer.android.com/training/location/index.html
where Google now states
"The Google Play services location APIs are preferred over the Android framework location APIs (android.location) as a way of adding location awareness to your app. If you are currently using the Android framework location APIs, you are strongly encouraged to switch to the Google Play services location APIs as soon as possible. "