Building on macos with the Qt6 framework.

made changes to several files to make it possible to build subsurface
desktop with the Qt 6.5.x and higher framework.

Tested versions: 6.5.2, 6.6.3, 6.7.2

code builds and googlemaps works, made some adjustments to get panning
and zooming with mouse or trackpad working.

See issue subsurface#3577 "Build Fails, macOS" for build details.

Signed-off-by: Egbertdepauw <egbert@despaankamer.nl>

There was an unneeded line in the code, just for my own testing
purposes.

Signed-off-by: Egbertdepauw <egbert@despaankamer.nl>