Make likes on comments update live via websockets

[jahooma]

When a user hits like, it calls our 'react' endpoint in reaction.ts. We need to broadcast the updated comment, which has its number of likes cached (currently we only have a websocket event for new comments), and subscribe in the client to comment changes sent via the websocket.

Can you do this @mentatbot ?

[mentatbot[bot]]

I will start working on this issue