mod(element): introduce deinit interface for deinitializing Elements automatically with the Container

examples/elements/input.zig

@@ -73,8 +73,6 @@ pub fn main() !void {
     defer renderer.deinit();
 
     var input_field: App.Input(.accept) = .init(allocator, &app.queue, .init(.black, .blue));
-    defer input_field.deinit();
-
     var mouse_draw: MouseDraw = .{};
     var second_mouse_draw: MouseDraw = .{};
     var quit_text: QuitText = .{};