widget: Redo how gtk_widget_queue_draw() works

widget: Redo how gtk_widget_queue_draw() works

Before, we would immediately invalidate the GdkWindow of the widget, now
we call the parent's GtkWidgetClass.queue_draw_child() function.
This allows the parent to track redraw queueing of children.

By default GtkWidgetClass.queue_draw_child() will again chain up to its
parent while respecting the GdkWindow hierarchy for clipping.
GtkWindow is then the only widget actually invalidating the GdkWindow.

This essentially moves redraw queueing from GDK to GTK.