Add possibility to use keycloak authentication token

[anikaweinmann]

This merge requests allows to use a keycloak token for authentication, where the user attributes, role and group have to be included.

The changes includes:

• creation of a ActiniaUserBase where the original ActiniaUser inherit from
• Adding a new ActiniaKeycloakUser class which is used when it is configured in the config file via:

If the keycloak authentication token is configured the basic authenication will not work at the same time.