Use prisma accounts in backend

[malteish]

see #1091

• store accounts in prisma instead of redis in backend
• add scripts and notes for manual migration of existing accounts (formerly sessions) from redis to prisma
• separate profile management in backend and delivery service, as the overlap now is negligible
• extend account table to include created at
• clean up libraries, improving structure. server-side and delivery saw most changes and have been detangled significantly.
• we used to have 2 files named Auth.ts and auth.ts. Imo Auth.ts handles authentication and is currently still called Auth.ts, while auth.ts handles authorization and has been renamed to authorize.ts. This starts a cleanup process that will be continued later, but this PR is already large enough.
• move socketAuth to delivery-service (from server-side), because it is used only there