Implement easy and performant room building concept.

[Myrmod]

We need a way to build rooms using this library. Currently I implemented the first step in https://doc.babylonjs.com/guidedLearning/workshop/House#the-function-and-how-to-use-it, which you can see https://svelte-babylon.netlify.app/examples/room.html in action.

However I am not sure if this is the best way to do it, since it is quite complicated.

I asked the folks at babylonjs how to go on about this at: https://forum.babylonjs.com/t/most-performant-way-to-build-a-house-with-multiple-rooms/28437

Feel free to post any suggestions on how you would like to be able to "build" a house or rooms.