RBAC - Add possibility to change consumersGroup role

[damien-malescot]

Is your feature request related to a problem? Please describe.
In JulieOps all consumersGroup's binding are set to RESOURCE_OWNER.
It will be great to add ability to change consumersGroup role in topology files.

Describe the solution you'd like
Here :
https://github.com/kafka-ops/julie/blob/master/src/main/java/com/purbon/kafka/topology/roles/rbac/RBACBindingsBuilder.java#L151

In topology we would like to be able to change group-role like this

    consumers:
      - principal: "Group:CONSUMER_READ"
        group-role: DeveloperRead
      - principal: "Group:CONSUMER_VIEW"
        group-role: DeveloperRead

If group-role is not set, fallback to default : RESOURCE_OWNER