[external-dns-management]

Action Required

[OPERATOR] If dns-controller-manager is used on clusters not created ("shooted") by Gardener and you are using (#123, @MartinWeindel)
- the source controllers with different default and target clusters, you are now required to provide an id for the default cluster explicitly. No non-unique default value is assumed anymore in this case.
- There are two ways to provide it.
- Use the command line option --kubeconfig.id or the corresponding value configuration.kubeconfigId for the helm chart
- Or alternatively you can create a configmap cluster-identity on the default cluster. See examples/15-cluster-identity.yaml for concrete structure.

[OPERATOR] use component prefix for prometheus metrics names (#126, @MartinWeindel)
[OPERATOR] support migration of resources.gardener.cloud/owners with the --migration-ids option (#123, @MartinWeindel)