Oasis installation and registration

• get users from central nomad (and not keycloak) -> no oasis admin required
• register oasis in mongo (e.g. when it gets the users)
• transfer some telemetry data upon registration
• gui view that lists registered oasis

A general fastapi middleware could be run for each API request on the Oasis installation. If the last "registration" is older than a configurable amount of time a new "registration" is perform. To do a "registration" the Oasis installation would call a respective API on the configured "central" installation. This simple POST API, would allow to send oasis id, oasis url, oasis maintainer, nomad version, and a few "telemetry" data (e.h. number of uploads, number of entries). The API of the "central" installation would store these registrations in mongodb. Based on this data in mongodb, we could look for suitable aggregations and visualisations of these registration data to represent the NOMAD/FAIRmat network of installations.