prof calendars with oauth2 login

We could provide prof. calendar with ldap login and check if its a professor and only create a personal calendar if the name and prof attribute matches. It is currently already possible to create and retrieve such calendars. However, the user must know exactly which modules the lecturer or professor is currently teaching.

• check keycloak login issue
• create login panel / prof panle for calendar creation
• add/edit backend api for security and responding informations