New homepage

[jbaicoianu]

We're still using the old Native-app-centric website for https://www.janusxr.org/ and we're pointing the web client to https://vesta.janusxr.org/ as our default start room.

We need to update the main page to reflect the fact that the web client is the primary client. It seems like the best route would be to come up with a new start room which showcases some of the new stuff that's possible with the web client, and use that as the background for our 2d website, using the scrollpath component or some camera LERPing to ease people in from the 2d site into the 3d world.