RBAC: Implement a default role

[Shawcs]

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?

If the UI have RBAC role defined and a user come with an identity that doesn't belong to any of this roles then the UI display nothing (like no cluster found)

Describe the feature you're interested in

A way to solve that would be to define a default role in the RBAC config of the Kafka-ui. In my mind it would be a Read only role by default, but user could want something else. So just been able to define a role by default with a list of permissions would be the best option I think.

Describe alternatives you've considered

No response

Version you're running

custom build 3740

Additional context

No response