Resolve [IP2WS2324G2-257] and [IP2WS2324G2-256]

• Outsourced Random algorithm and its logic into backend
• created some utils files for reusable functions
• deleted unsued functions, imports variables in waitingroom.ts (frontend)
• fixed changed some any types into actual types in backend
• added new db table in order to map user to a waitingroom and adjusted db querys
• added code comments to in mainly in group.routes.ts
• adjusted and added some apidocs to routes
• adjusting websocket connection failed
• waitingroom attribut status will get changed after groups are created (so waitingroom wont be accessable)
• fixed typo errors
• made waitingroom.ts run asynchronously
• established backend and idea for backend folder structure