Implement GtkColorPicker for Windows
Right now we have implementations of GtkColorPicker for:
- Gnome Shell
- KWin
- fd.o portals
It would be nice to have an implementation also for Windows. We can follow the implementation in GIMP3: https://gitlab.gnome.org/GNOME/gimp/-/blob/master/libgimpwidgets/gimppickbutton-default.c