Clean up example into its own directory

[JoelCreatesGames]

I found importing this asset to be a bit confusing because the example is at the root directory. This PR cleans that up by making an example folder and cleaning some things up (removing empty Node.gd file for example).

Changes:

• imported in Godot 4.1 (some import setting changes)
• moved to example directory and cleanup
  • fixed paths for preload of ChatMessage
• Renamed scene to Example (and root node name)
• Added moderator:read:followers to default scopes as example needs it for channel.follow event
• Updated README:
  • added note about example auth file (and updated it to be .txt as godot lets you create those in editor)
  • link to example script

[issork]

Thanks!