gdkcursor-win32.c: Add cursor map for all-scroll (issue #3581)

Hi,

From the commit message:

This makes sure that we don't have cursors disappearing on Windows upon scrolling because we can't find a cursor that exists on the system during a scroll, and unlike GTK-3.x, we do not default to the arrow pointer on GTK4.

Just mimic what we have on X11 and Wayland: the trusty standard arrow pointer.

Fixes issue #3581 (closed).

This will be for the master and gtk-4.0 branch.

With blessings, thank you!