widget: Queue redraw on gtk_widget_queue_allocate()

widget: Queue redraw on gtk_widget_queue_allocate()

Mirror the behavior of gtk_widget_queue_resize() and always queue a
redraw. If we ever want to cause allocates without redraws we can add
gtk_widget_queue_allocate_no_redraw() then.

I had initially assumed gtk_widget_size_allocate() would take care of
queueing redraws, but it does not do that when neither size nor position
change. And that is obviously what's happening after
gtk_widget_queue_allocate().

Fixes buttons sometimes not redrawing (the record button in
widget-factory after locking it, all buttons when switching to the dark
theme).