Automatic merge from submit-queue
Populate Node.Status.Addresses with Hostname
This PR is supposed to address #22063
Currently `NodeName` has to be a resolvable dns address on the master to allow apiserver -> kubelet communication (exec, log, port-forward operations on a pod). In some situations this is unfortunate (see the discussions on the issue).
The PR aims to do the following:
- Populate the `Type: Hostname` in the `Node.Status.Addresses` array, the type is already defined, but was not used so far.
- Add logic to resolve a Node's Hostname when the apiserver initiates communication with the Kubelet, instead of using the Nodename string as Hostname.
```release-note
The hostname of the node (as autodetected by the kubelet, specified via --hostname-override, or determined by the cloudprovider) is now recorded as an address of type "Hostname" in the status of the Node API object. The hostname is expected to be resolveable from the apiserver.
```
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