CLONE - QtLocation maps to Qt 6.2

I have started to port QtLocation maps to Qt 6.2 and this issue is to track and collect all the relevant information.

Current status:

• All classes are included into CMake build and modified for Qt 6.
• OpenGL backend code of MapPolyline, MapPolygn, MapcCircle and MapRectangle (including labs project) is ported to new abstract graphics API.
• MapboxGL plugin is re-introdced as MaplibreGL plugin. It compiles on MSVC, Android and iOS but is pointed to a fork of maplibre repository because it needs changes to be merged into the main repo.

Bigger modifications:

• Mouse and touch input part is re-written to support new 'exclusiveGrabber' and to be able to share different touch point between different child items. For example, one finger can pan the map and another finger can scroll child ListView.

Known issues:

• Map tiles are not visible during flick animation. But they are when performing 'center' property CoordinateAnimation on the QML side. No idea, what's the cause. Flick movement is basically the same, only on the C++ side. Fixed with https://codereview.qt-project.org/c/qt/qtlocation/+/373996
• MapPolyline extruded version has scrambled miter joints when route/polyline contains equal coordinates twice in the path, next to each other. Seems that routes can have this, when it contains multiple route segments or something. But, the same behaviour is in Qt 5.
• WIP: "mapboxgl" plugin has been switched to Maplibre. I compiles and works. TODO: rename everything an re-introduce it a "maplibregl" plugin.
• Tests are not included. https://codereview.qt-project.org/c/qt/qtlocation/+/380646/8
• Examples are not yet ported/included.