remove audio from lobby

[stilnat]

Summary

Make ambient sounds only play when onboarding.

PR checklist

• The game builds properly without errors.

• No unrelated changes are present.

• No "trash" files are committed.

• Relevant code is documented.

• Update the related GitBook document, or create a new one if needed.

Pictures/Videos)

Testing

Networking checklist

• Works from host in host mode.

• Works from server in server mode.

• Works on server in client mode.

• Works and is syncronized across different clients.

• Is persistent.

Changes

Just added an event in the entity system. When a player spawn, a target rpc is sent to the client spawning, and the onSpawned event is called. The ambiant system suscribes to that.

Related issues/PRs

closes #1352