Downstream CI: Setup acceptance pipeline against each index image built via CPaaS

• Our umb listener service have to be configured to receive message from topic `VirtualTopic.eng.ci.redhat-container-image.test.complete` and filter messages based on NVR of our product `openshift-gitops-operator-bundle`

• Trigger an acceptance pipeline based on new index image on respective ocp version specified in build metedata information.

Acceptance criteria:

• Expected to have atleast 1 pipelines run(s) for each ocp version of cpaas build(index image)
• New Index image should trigger respective acceptance tests by parsing index image, ocp version, channel and run tests against kuttl tests against right branches.
• And expected to send slack notifications. 
• Update documentation