[dagit] Refactor components with subscriptions

Summary:
There are three components that use DirectGraphQLSubscription. Refactor these to be SFCs. The next objective here will be to grab more information about the WebSocket connection from context: namely, connection parameters that could be defined at the application root. These would currently be ignored because the DirectGraphQLSubscriptions are independent of the WebSocketLink set up in AppProvider.

Next steps:

• Modify WebsocketStatusProvider to supply more values intended for WebSocket usage
• Move the SubscriptionClient in AppProvider to WebsocketStatusProvider
• Delete WebSocketLink from AppProvider, because we don't really use it

Test Plan:
View runs in Dagit, start a few. Verify that WebSockets are set up correctly, receive messages as intended, and results are rendered properly as they arrive.

Start Dagit with grpc, restart grpc. Verify that the repository location observer shows the appropriate message in the left nav.

Reviewers: bengotow, prha, dgibson

Reviewed By: bengotow

Differential Revision: https://dagster.phacility.com/D9087