Integrate @withso/pop-media-sdk to allow different media providers

[a-type]

This PR replaces PopSpace's old media setup (with hardcoded Twilio) and uses @withso/pop-media-sdk and associated packages instead, allowing the app to utilize either Twilio or LiveKit as the backing media provider.

To use Twilio, you must provide the environment variable REACT_APP_USE_TWILIO=true along with the existing Twilio environment variables.

To use LiveKit, provide REACT_APP_USE_LIVEKIT=true instead, and add the required config variables:

# required for the noodle-app package (React app)
REACT_APP_LIVEKIT_ENDPOINT=https://your-livekit-endpoint.com
# required for the noodle-api package (the HTTP API)
LIVEKIT_API_KEY=your-livekit-api-key
LIVEKIT_SECRET_KEY=your-livekit-secret-key