Add a notification system

[Ategon]

There should be a way for different things in the backend to call a function to make a notification. There should be different notification types and then there should be a way to retrieve notifications (all of them or specific types)

Certain notifications in the frontend would allow people to hit buttons to accept or deny them (e.g. team applications), others might inline have a way to bring up a textbox to reply (e.g. game comments)

All notifications would persist in the users notification section until they hit a mark as read button (or the confirm or deny buttons if its one of those or reply if its one of those. The notifications that show accept or deny should not have a mark as read button)

Notification types are:

• Team application (someone applied to join your team) (accept/deny)
• Team application accept (someone accepted your team application) (regular)
• Team application deny (someone denied your team application) (regular)
• Team invite (you were invited to a team) (accept/deny)
• Team invite accept (the person you invited accepted your invite) (regular)
• Team invite deny (the person you invited denied your invite) (regular)
• Team leave (someone left your team) (regular)
• Team join (someone joined your team) (regular)
• Game comment (reply)
• Comment reply (reply)
• Post reply (reply)
• Follow (someone followed you) (follow)
• Game follow (someone followed your comment section) (regular)
• Post follow (someone followed your post comment section) (regular)
• Post Mention (someone mentioned you in a post) (reply)
• Comment Mention (someone mentioned you in a comment) (reply)