Cache live chat history on client side

[akshitdewan]

Currently, you don't have any history available for live chat when opening a new student's request. You also lose history if you switch to another page on the website. A possible solution is to cache the messages sent in the react state so that once you have opened the window, you will receive all messages sent.

The relevant component to look at is chat_box.js. This change would involve adding the chat messages to the state in app.js, using a socket.on("chat_message") in order to update this state and passing this state down to AppointmentLayout and TicketLayout.