Streamline access permissions across catalog, query engine and superset

We don't have a harmonized system for access permissions across the various applications. Currently we

- deploy Keycloak as an identity provider for the Lakekeeper catalog. It connects to LDAP for authentication.
- connect Superset directly to LDAP for authentication and use its own roles mechanism for assigning permissions to datasets.
- connect Trino to Keycloak for authorisation and define access rules in Trino

As more people and groups get onboard this will become a challenge to manage. We should aim to centralize all of this information such that it is consistent across all of the catalog access points, namely BI tools (superset) & programmatic tools (Python/PyIceberg/).

Useful links:
- https://docs.lakekeeper.io/docs/nightly/authorization/: See OpenFGA, OPA & Trino.
- Superset user groups: [User Groups for Simplified User and Role Management](https://github.com/apache/superset/issues/32116)