commands/focus: focus floating windows when moving across outputs

Moving focus directionally to an output containing only floating windows
would previously focus the workspace instead of the previously focused
floating window. This change falls back to the inactive focus, to match
the behaviour of workspace_switch().

sway/commands/focus.c

@@ -132,7 +132,7 @@ static struct sway_node *get_node_in_output_direction(
 		return &container->node;
 	}
 
-	return &ws->node;
+	return seat_get_focus_inactive(seat, &ws->node);
 }
 
 static struct sway_node *node_get_in_direction_tiling(