A transport may soon carry a LiveKit SFU `url` instead of, or as well as,
a `livekit_service_url`, so a service URL alone no longer identifies it.
Pass the whole transport to the tiles' debug stats and print it as JSON in
log lines instead of picking out the service URL.
The rule of thumb to avoid resource leaks is that you should never call ObservableScope methods in a callback unless the ObservableScope is directly passed to or created inside that callback. I had a go at codifying this as a lint rule.
Robin