RBAC: Allow "all" operator in the clusters' list

[nicklev]

Issue submitter TODO list

• [X] I've searched for an already existing issues here
• [X] I'm running a supported version of the application which is listed here and the feature is not present there

Is your proposal related to a problem?

No response

Describe the feature you're interested in

Hello,

I want to assign view or admin permissions automatically to new Kafka clusters. For that reason, it would be great if there was an "all" or "*" operator under clusters' list.

For example, see the following configuration sample:

rbac:
  roles:
    - name: "readonly"
      clusters:
        - all (or *)
      subjects:
        - provider: ldap
          type: group
          value: "XXX"
      permissions:
        - resource: XXX
          actions: [ "view" ]

Describe alternatives you've considered

No response

Version you're running

83b5a60

Additional context

No response