Implement the KRShaped interface in Eventing

[whaught]

Problem
In the upstream knative.dev/pkg repo I've created a new interface that specifies accessors for resources that conform to the duckv1 shape with a duckv1.Status, objectmeta, and type meta.

https://github.com/knative/pkg/blob/66f1d63f10199087aa2aada31a07f25f516fadd0/apis/duck/v1/kresource_type.go#L30

We use this to automatically handle ObservedGeneration (and future common logic) from the generated reconciler code. This issue is to track adoption of the interface for Eventing.

Here's a model PR from serving: knative/serving#7878

Persona:
Which persona is this feature for? Contributors

Time Estimate (optional):
How many developer-days do you think this may take to resolve? 1

Additional context (optional)
This should be mostly copy-paste from the model PR and should be straightforward. However it might be a good-first-issue for someone trying to learn about our API structure.

Reporting a condition-set for Broker may have additional caveats. See: #3094

[whaught]

/assign

[whaught]

/close

[knative-prow-robot]

@whaught: Closing this issue.

In response to this:

/close

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