feat(helm): publish OCI helm charts

[M0NsTeRRR]

Description

publish OCI helm-charts see helm docs
As kubernetes-sigs/external-dns/external-dns is already used by the docker image, I've used kubernetes-sigs/charts/external-dns.

Fixes #4630

Checklist

• Unit tests updated
• End user documentation updated

[k8s-ci-robot]

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[k8s-ci-robot]

Hi @M0NsTeRRR. Thanks for your PR.

I'm waiting for a kubernetes-sigs 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.

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[stevehipwell]

@M0NsTeRRR publishing the chart via OCI isn't currently supported due to not having a target that's been blessed by the kubernetes-sigs group. I've been chasing this up for years as it's not just an ExternalDNS concern, but I've not made any progress.

/hold