Add a built-in web server to distribute resource packs

Is your feature request related to a problem? Please describe. Although client-side spawner support has already been added, there's still the last step: send the resource pack to client, which needs a web server holding resource pack files.

Describe the solution you'd like It's obviously the best to reuse the port that the Minecraft server owns, which can be achieved by some existing projects.

Describe alternatives you've considered Another acceptable solution is to occupy another port for the web server.