Configures the `Kafka` custom resource to use Open Policy Agent authorization.

To use link:https://www.openpolicyagent.org/[Open Policy Agent^] authorization, set the `type` property in the `authorization` section to the value `opa`,
and configure OPA properties as required.
Strimzi uses the Open Policy Agent plugin for Kafka authorization as the authorizer.
For more information about the format of the input data and policy examples, see {OPAAuthorizer}.

The `type: opa` authorization is now deprecated and will be removed in the future.
If you want to use the Open Policy Agent authorizer, you should use the `type: custom` authorization.

.Example Open Policy Agent authorizer configuration using the `type: custom` API
[source,yaml,subs=attributes+]
----
apiVersion: {KafkaApiVersion}
kind: Kafka
metadata:
  name: my-cluster
  namespace: myproject
spec:
  kafka:
    # ...
    authorization:
      type: custom
      authorizerClass: org.openpolicyagent.kafka.OpaAuthorizer
      superUsers:
        - CN=user-1
        - user-2
        - CN=user-3
    config:
      # OPA authorization options
      opa.authorizer.url: http://opa:8181/v1/data/kafka/allow
      opa.authorizer.cache.expire.after.seconds: 60
      opa.authorizer.allow.on.error: false
      opa.authorizer.cache.initial.capacity: 1000
      opa.authorizer.cache.maximum.size: 10000
    # ...
----

