Add friends list

[NikhilNarayana]

Friends list should be part of the user's data on the website so this will require some supervision from Fizzi.

Add friends manually or from the replay browser. Website backend should provide desktop app with list of friends. friend requests, and declined friend requests. Friend requests should be accepted or declined. Declined friend should not be able to re-request unless the user clears the decline.

Some method of communication might be fine, to say invite a friend to play some games. It would be nice to have discord integration at this point so that users can share their discord with added friends.