[Feature Request]: Directory synchronization Keycloak / Group mappers

**Is your feature request related to a problem? Please describe.**
No, more like less human interaction and better end user experience when using keycloak as OIDC provider.

**Describe the solution you'd like**
After user login with keycloak as external OIDC provider we need to map the users by hand to a group. So it would be better to use group mappers so that we can map the keycloak groups to the Defguard groups and we dont have to add the users to a group.

With this solution the user dont have to wait for human intervention to connect to the network after they log in for the first time.
Also after that, the user needs to be synct regularly because it could be that the groups changed in Keycloak.