User Authorization Middleware

[Mohido]

This middleware will use the keycloak realm roles to authorize a logged in user. It checks if the user request is valid to use these this endpoint or not. For this project, we need two middlewares:

• isAdmin
• isStudent

[Mohido]

This one is not needed anymore. We don't need an authorization middle ware for this web application. We might need to reopen this if we need extra authorizations (For accessing exams or whatsoever).