[Operator] Integration with Knative Eventing

The current integration with Knative eventing is done through a xml snippet  similar to this one:
 

 <cloudevents bootstrap-servers="127.0.0.1:9092" acks="0" audit-topic="audit" cache-entries-topic="cache-events"/>

The operator must allow to:

• Define all the required parameters for the integration in the Infinispan CR
• Inject the right fragment into Infinispan.xml

The Infinispan CR will have the following form:

cloudevents:
    bootstrap-servers:
    acks: [default: all (SYNC) | 0 (ASYNC)]
    cache-entries-topic: