Closes: https://gitlab.gnome.org/GNOME/gtk/issues/1737
Don't export any functions taking or returning MacOS types in
gdkquartz.h, gdkprivate-quartz.h, or any header that either includes.
The GdkQuartz internal functions are moved to a new header
gdkinternal-quartz.h, the functions used by quartz-specific
Gtk files are moved to another new header gdkquartz-gtk-only.h, and
the key and event enums to a new header gdkkeys-quartz.h.
We've long had double precision mouse coordinates on wayland (e.g.
when rotating a window) but with the new scaling we even have it on
X (and, its also in Xinput2), so convert all the internal mouse/device
position getters to use doubles and add new accessors for the
public APIs that take doubles instead of ints.
