Cloud events per namespace

Feature request

In our setup, we have a large number of namespaces, each with their own custom pipelines as well as their own event listeners.

As I understand, we are allowed to provide a single sink for cloud events by specifying default-cloud-events-sink in the config-defaults config map in the tekton-pipelines or openshift-pipelines namespaces (n.b. I suppose this has been changed to the config-events config map).

IMO this approach comes with some limitations:

1. We are not able to customize the sink per namespace.
2. We are not able to filter out events per namespace.
3. This functionality also presumes that we have access to the tekton-pipelines or openshift-pipelines namespaces (in our environment this access is limited to the cluster admins).

Use case

It would be very useful to be able to respond to events such as pipeline completion by listening to these events (i.e. isolated per namespace). This could potentially initialize a separate pipelinerun (which is part of the design we are trying to implement).