Add Deprecation Warnings to Topic and PullSubscription

[Harwayne]

Helps with #905.

Proposed Changes

• Add deprecation warnings to every Topic and PullSubscription in the pubsub.cloud.google.com API group.

  - lastTransitionTime: "2020-05-01T22:56:05Z"
    message: This Kind is deprecated and the CRD has been made 'internal'. This
      means, end-users should not create objects of this CRD directly. If you need
      a non-internal variant, then please let us know by commenting on https://github.com/google/knative-gcp/issues/905.
      Moreover, the object must be deleted before upgrading to 0.16 to avoid orphaning
      the Google Cloud Platform resources that were created on-behalf of this object,
      such as Pub/Sub Topics and Subscriptions.
    reason: willBeRemoved
    severity: Warning
    status: "True"
    type: Deprecated

Release Note

All `Topic` and `PullSubscription` objects in the `pubsub.cloud.google.com` API group will have deprecation warnings in their status. Those objects will no longer exist in the 0.16 release. All `Topic` and `PullSubscription` objects created by other reconcilers within `knative-gcp` will automatically migrate to the replacements without user interaction. **Migration may cause back logged events to be lost.**

[Harwayne]

/test pull-google-knative-gcp-integration-tests

[Harwayne]

/hold

Holding to allow @akashrv to confirm or alter the deprecation message.

[akashrv]

Content is correct. We could mellow down a bit. How about: "This object (or kind) is deprecated and the CRD is made 'internal'. This means, end-users should not create objects of this CRD directly. If you need a non-internal (or a public) variant, then please let us know by commenting on #905. Moreover, the object must be deleted before upgrading to 0.16 to avoid leaking (or orphaning) the Google Cloud Platform resources that were created on-behalf of this object, such as Pub/Sub topics and subscriptions."

[Harwayne]

Sounds good, how about (almost identical to yours, but removed the parenthesis):

This Kind is deprecated and the CRD has been made 'internal'. This means, end-users should not create objects of this CRD directly. If you need a non-internal variant, then please let us know by commenting on https://github.com/google/knative-gcp/issues/905. Moreover, the object must be deleted before upgrading to 0.16 to avoid orphaning the Google Cloud Platform resources that were created on-behalf of this object, such as Pub/Sub Topics and Subscriptions.

[akashrv]

/LGTM

[Harwayne]

/hold cancel

Cancelling hold now that the wording has been agreed upon.

[Harwayne]

Ping.

[grantr]

Sorry for the delay in reviewing. Only minor nits, cancel the hold if desired.

/lgtm
/hold

[grantr]

/lgtm
/hold cancel

[Harwayne]

/retest

[grantr]

/lgtm

[knative-prow-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: grantr, Harwayne

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[Harwayne]

/retest

[Harwayne]

/retest

[Harwayne]

/retest

[knative-metrics-robot]

The following is the coverage report on the affected files.
Say /test pull-google-knative-gcp-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/apis/pubsub/internal/deprecated_condition.go	Do not exist	100.0%
pkg/apis/pubsub/v1alpha1/deprecated_condition.go	Do not exist	0.0%
pkg/apis/pubsub/v1beta1/deprecated_condition.go	Do not exist	0.0%
pkg/reconciler/pubsub/topic/topic.go	69.6%	69.9%	0.3

[knative-prow-robot]

@Harwayne: The following tests failed, say /retest to rerun all failed tests:

Test name	Commit	Details	Rerun command
pull-google-knative-gcp-build-tests	d275fae	link	/test pull-google-knative-gcp-build-tests
pull-google-knative-gcp-go-coverage	3693559	link	/test pull-google-knative-gcp-go-coverage

Full PR test history. Your PR dashboard.

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