Automatic merge from submit-queue (batch tested with PRs 42058, 41160, 42065, 42076, 39338)
[Federation] Create configmap for the cluster kube-dns when cluster joins and remove when it unjoins
This PR implements the functionality as needed in https://github.com/kubernetes/kubernetes/issues/38400
cc @kubernetes/sig-cluster-federation @nikhiljindal @madhusudancs
**Release note**:
```
kubefed join can now automatically create a configmap or add information to already existing one, storing this federation name vs zone name information in the joining cluster.
Further kubefed unjoin can remove this configmap or only this information from the configmap, if the unjoin cluster is registered with multiple federations.
The name of the configmap is kube-dns and the information in it is consumed by the in-cluster dns server.
```
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