QGeoPositionInfoSource on Android always asks for location permission

While updating an app from Qt 5.12 to 5.15 and debugging location permission dialogs appearing before the app being visible, I found QTBUG-81689.

In this change, lastKnownPosition() was changed to always ask for permissions on Android which is wrong in my opinion. The CoreLocation implementation of this function just returns the last known position without asking for permission as the documentation describes it.

The QML element PositionSource on Android now asks for permissions when it is being created since componentCompleted() inserts the last known position. This makes its "active" parameter completely useless since there is no way to control when the permission dialog should appear.