Switch to CRDs v1

[matzew]

/area API
/kind process

#Describe the feature
Since https://github.com/knative/pkg/pull/1391/files happened, we should be able to adopt the apiextensions.k8s.io/v1 apiGroup.

[knative-prow-robot]

@matzew: The label(s) kind/process cannot be applied, because the repository doesn't have them

Details

In response to this:

/area API
/kind process

#Describe the feature
Since #6582 happened, we should be able to adopt the apiextensions.k8s.io/v1 apiGroup.

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[matzew]

For serving project there is already a PR from @dprotaso for this: knative/serving#8259

[matzew]

/assign