Report Supported Features to Frontend

[bennettrwu]

whisper-service and node-server should report which models (list of model_keys) whisper-service is configured with. In addition, for each model_key, which features (phrase lists, language) are supported.

• Enable node-server to fetch supported models and features from whisper-service via http request
• node-server should send supported models to frontend via websocket immediately after authentication

Note: Depends on #12