Add Support for Cloudflare

[hyperkineticnerd]

This PR adds support for Cloudflare DNS.

The following manifests are currently being used in production:

apiVersion: externaldns.olm.openshift.io/v1beta1
kind: ExternalDNS
metadata:
  name: cloudflare-service
spec:
  provider:
    cloudflare:
      credentials:
        name: cloudflare-credentials
      proxied: false
    type: Cloudflare
  source:
    hostnameAnnotation: Allow
    type: Service
    service:
      serviceType:
        - NodePort

apiVersion: externaldns.olm.openshift.io/v1beta1
kind: ExternalDNS
metadata:
  name: cloudflare-ingress
spec:
  provider:
    cloudflare:
      credentials:
        name: cloudflare-credentials
      proxied: false
    type: Cloudflare
  source:
    hostnameAnnotation: Allow
    ingress: {}
    type: Ingress

The previous manifest is using some preliminary Ingress.networking.k8s.io support too.

[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: Once this PR has been reviewed and has the lgtm label, please assign alebedev87 for approval. For more information see the Kubernetes Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files: - **[OWNERS](https://github.com/openshift/external-dns-operator/blob/main/OWNERS)** Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[openshift-ci[bot]]

Hi @hyperkineticnerd. Thanks for your PR.

I'm waiting for a openshift member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes/test-infra](https://github.com/kubernetes/test-infra/issues/new?title=Prow%20issue:) repository.

[openshift-bot]

Issues go stale after 90d of inactivity.

Mark the issue as fresh by commenting /remove-lifecycle stale. Stale issues rot after an additional 30d of inactivity and eventually close. Exclude this issue from closing by commenting /lifecycle frozen.

If this issue is safe to close now please do so with /close.

/lifecycle stale

[openshift-bot]

Stale issues rot after 30d of inactivity.

Mark the issue as fresh by commenting /remove-lifecycle rotten. Rotten issues close after an additional 30d of inactivity. Exclude this issue from closing by commenting /lifecycle frozen.

If this issue is safe to close now please do so with /close.

/lifecycle rotten /remove-lifecycle stale

[openshift-bot]

Rotten issues close after 30d of inactivity.

Reopen the issue by commenting /reopen. Mark the issue as fresh by commenting /remove-lifecycle rotten. Exclude this issue from closing again by commenting /lifecycle frozen.

/close

[openshift-ci[bot]]

@openshift-bot: Closed this PR.

In response to [this](https://github.com/openshift/external-dns-operator/pull/200#issuecomment-1965981399): >Rotten issues close after 30d of inactivity. > >Reopen the issue by commenting `/reopen`. >Mark the issue as fresh by commenting `/remove-lifecycle rotten`. >Exclude this issue from closing again by commenting `/lifecycle frozen`. > >/close Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes/test-infra](https://github.com/kubernetes/test-infra/issues/new?title=Prow%20issue:) repository.