Defining a path to Beta for DNSEndpoint API

Based on proposal https://github.com/kubernetes-sigs/external-dns/blob/master/docs/proposal/003-dnsendpoint-graduation-to-beta.md

Core:

• Move code to api/v1alpha
• Status is missing
• Metrics missing
• Events missing https://github.com/kubernetes-sigs/external-dns/pull/5659

Relevant Issues

• motivation https://github.com/kubernetes-sigs/external-dns/issues/2941
• https://github.com/kubernetes-sigs/external-dns/issues/2936
• https://github.com/kubernetes-sigs/external-dns/issues/4859
• https://github.com/kubernetes-sigs/external-dns/issues/2308
• https://github.com/kubernetes-sigs/external-dns/issues/3634
• https://github.com/kubernetes-sigs/external-dns/issues/4859
• https://github.com/kubernetes-sigs/external-dns/issues/2092
• not sure if relevant https://github.com/kubernetes-sigs/external-dns/issues/4792
• https://github.com/kubernetes-sigs/external-dns/issues/5254
• https://github.com/kubernetes-sigs/external-dns/issues/646
  • https://github.com/kubernetes-sigs/external-dns/pull/821/files
• https://github.com/kubernetes-sigs/external-dns/issues/4575
• https://github.com/kubernetes-sigs/external-dns/issues/1961
• https://github.com/kubernetes-sigs/external-dns/issues/4575
• https://github.com/kubernetes-sigs/external-dns/issues/5243
• https://github.com/kubernetes-sigs/external-dns/issues/3634
• https://github.com/kubernetes-sigs/external-dns/issues/6030
• https://github.com/kubernetes-sigs/external-dns/issues/5741

Beta candidate

• https://github.com/kubernetes-sigs/external-dns/issues/3163

Resources

• https://book-v1.book.kubebuilder.io/basics/status_subresource.html

Encrich status

• https://github.com/kubernetes-sigs/external-dns/issues/5243#issue-2964468706

Please add here issues, bugs missed features related to DNSEndpoint