live/infer: Add trickle input and output

[j0sh]

Logging is still rough as I'm ironing out issues around tear-down, but wanted to put this out

Should be testable with

 curl -vvv http://localhost:9000/live-video-to-video/ -H 'Content-Type: application/json' -d '{"subscribe_url":"http://trickle-server/input-stream","publish_url":"http://trickle-server/output-stream"}'

[j0sh]

@victorges Just a heads up that the publish task hangs after the input stream completes. I am not sure exactly how the other parts work but you will need to call publish_queue.put(None) after receiving a None from subscribe_queue (or waiting for subscribe task completion, eg await subscribe_task that is created here. This can also be used as a signal to clean up the inference job.

For reference, here is how I have been driving the process (without inference)