bug: ID clashes in client creation in different namespaces and datasets

When creating a client in a namespace, the client ID will clash without the user knowing as the ID used for creation is used verbatim in keycloak.

Reproducer:

1. create a client with ID client-1 in a namespace or dataset
2. create a second client with ID client-1 in a separate namespace or dataset
3. 500 error is thrown, no client gets created

We expose both client ID and name setting so users can avoid it but still

Solution would be to add some DS / NS identification to the client ID or just use generated UUID as well that are referred to in the UI via a Client Name.

Another option is to provide better handling of this error, as right now a 500 error is surfaced without any information