Flip storage versions of Sources, topic, pullSubscription to v1 and add migration tool

[danyinggu]

Fixes #1482

Proposed Changes

• Flip storage versions of all Sources except CloudBuildSource, Topic and pullSubscription from v1beta1 to v1.
• Add migration tool for all above resources.
• There will be a separate PR to flip served bits of deprecated v1alpha1 resources as this is a separate issue.

Release Note

Change storage versions of all below resources from v1beta1 to v1:
            - "cloudauditlogssources.events.cloud.google.com"
            - "cloudpubsubsources.events.cloud.google.com"
            - "cloudstoragesources.events.cloud.google.com"
            - "cloudschedulersources.events.cloud.google.com"
            - "pullsubscriptions.internal.events.cloud.google.com"
            - "topics.internal.events.cloud.google.com"

action required: You must run pre-install job prior to upgrading to get these resources to v1 API.
ko apply -f config/pre-install/v0.18.0/

Docs

[danyinggu]

The size of this PR is already huge. We will flip served bits of v1alpha1 Sources and Channel as a follow-up, as this is a separate issue from changing storage bits of v1.
I created a separate issue here #1645 to keep track.

[nachocano]

I think we need to add a new artifact to our release, so that we include the migration bits...
I think eventing does so, maybe you can do it in a follow up?

[nachocano]

/lgtm
/approve

I think we need something like: knative/eventing#3928
We can double check with @chizhg

[knative-prow-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: danyinggu, nachocano

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[nachocano]

/lgtm

[capri-xiyue]

/lgtm

[knative-test-reporter-robot]

The following jobs failed:

Test name	Triggers	Retries
pull-google-knative-gcp-integration-tests		0/3

Failed non-flaky tests preventing automatic retry of pull-google-knative-gcp-integration-tests:

test/e2e.TestChannelChain/Channel-messaging.cloud.google.com/v1beta1
test/e2e.TestChannelChain
test/e2e.TestEventTransformationForSubscription/Channel-messaging.cloud.google.com/v1alpha1
test/e2e.TestEventTransformationForSubscription