Implement chatting backend support.

[WilliamDormer]

I am unclear if this will need more than one endpoint. But it seems like we should use WebSockets to support live conversations between the users, and then save the chat when both users are offline to the Postgres, most likely in JSON format (unless there is a standard format that people use when doing this sort of thing). We just need someone to take the lead on implementing this. Ensure that when you are researching the right way to do this, you take into account that there must be a supported method on the frontend (flutter) to actually send the requests. So if there is no package that supports WebSockets in flutter (there probably is but check to be sure) then we cannot use that for the solution.
Here's the functionality we need:

• two users can communicate with each other using text and emojis
• A message sent by the other party should appear in a reasonable time frame (2 seconds)
• Messages should be persistent between sessions
• A user should be able to send a message asynchronously if the other person is offline.
• it should be able to show when the other person has seen a message (read recepits)
• it should be able to show when the other person is typing
• Ideally it should also be able to support other file types in the future (images, audio, video, gif etc)

[WilliamDormer]

got the basic shell working. Can send messages and join rooms/leave rooms. Need to add authentication, and a way to force people to only join rooms with their matches.

[WilliamDormer]

able to join rooms, send messages to other users. save messages to database. Still need to work on read recepits, typing indicators, and the UI display of images that are sent.