wire delivery through to subscriptions

[vaikas]

Fixes #2977

Proposed Changes

• Propagate SequenceStep.Delivery to underlying Subscription.
• Better error reporting in the status. Report the failed channel/subscription in the status.
• add failure tests, which led to above point.

Release Note

- 🐛 Fix bug
Sequence now properly propagates the Delivery options to underlying Subscriptions.

Docs

[knative-metrics-robot]

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

File	Old Coverage	New Coverage	Delta
pkg/reconciler/sequence/sequence.go	70.6%	79.1%	8.5

[n3wscott]

/lgtm
/approve

[knative-prow-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: n3wscott, vaikas

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[vaikas]

/test pull-knative-eventing-integration-tests

[vaikas]

well, that's a new one:

error: error when retrieving current configuration of:
Resource: "rbac.authorization.k8s.io/v1, Resource=clusterroles", GroupVersionKind: "rbac.authorization.k8s.io/v1, Kind=ClusterRole"
Name: "eventing-broker-ingress", Namespace: ""
Object: &{map["apiVersion":"rbac.authorization.k8s.io/v1" "kind":"ClusterRole" "metadata":map["annotations":map["kubectl.kubernetes.io/last-applied-configuration":""] "labels":map["eventing.knative.dev/release":"devel"] "name":"eventing-broker-ingress"] "rules":[map["apiGroups":[""] "resources":["configmaps"] "verbs":["get" "list" "watch"]]]]}
from server for: "STDIN": Get https://35.238.155.91/apis/rbac.authorization.k8s.io/v1/clusterroles/eventing-broker-ingress: error executing access token command "/google-cloud-sdk/bin/gcloud config config-helper --format=json": err=exit status 1 output= stderr=ERROR: gcloud crashed (OperationalError): database is locked
If you would like to report this issue, please run the following command:
  gcloud feedback

[vaikas]

/test pull-knative-eventing-integration-tests