chore: Adds scene (non-ui) example

# Description I'm interested in quill for managing the entity lifecycle of some UI elements in an app I'm building. The way the app's built, I don't need bevy_ui, just the ability to manage meshes and spatials (bevy is basically the canvas). This PR adds a bit of a kitchen sink example showcasing props, for loops, conditionals using `Element::<SpatialBundle>::new()`. ## Pictures ### Initial State <img width="1281" alt="Screenshot 2024-08-22 at 9 03 00 pm" src="https://github.com/user-attachments/assets/c1876389-5aac-4592-97eb-b2c26fd4d7b3"> ### After pressing space a few times. <img width="1278" alt="Screenshot 2024-08-22 at 9 03 14 pm" src="https://github.com/user-attachments/assets/899f86ef-9fa5-4b7e-9678-b88837e4d745"> ## Also Thanks for this project, I've seen the effort you've gone to in the discord and this library is incredible :)