Test element call

trafficlight-adapter-element-web uses cypress which provides a basic video feed for the webcam; i think it would be possible to run multiple element call clients to test as a group by sending their videos. Not sure how to receive the video back, but cypress does record something, so we can at least /look/ at what happens.

Start with the trafficlight-adapter-element-web Cypress setup and inspect how its basic webcam video feed is recorded. Determine how multiple Element Call clients could participate and how returned video would be observed or captured. Done should include a defined multi-client test flow and a way to inspect its video behavior.

Written by the indexing model from the issue text.