commands: when moving container, remove its gaps

sway/commands/move.c

@@ -231,6 +231,7 @@ static void container_move_to_container(struct sway_container *container,
 	struct sway_workspace *old_workspace = container->workspace;
 
 	container_detach(container);
+	container_remove_gaps(container);
 	container->width = container->height = 0;
 	container->saved_width = container->saved_height = 0;