…tl create/run` in case of conflict with terminated pods/jobs

    Fixes kubernetes#22986

    - added printing clarification on pod or job creation AlreadyExists error
      in case of the failure is due to conflicting with pod/job in terminated state
    - added warning description regarding terminated pods to `get` long help message
    - added printing of warning message in case of `get pods`

  - added warning description regarding terminated pods to `get` long help message
  - added printing of warning message in case of `get pods` if there are hidden pods
Fixes kubernetes#22986

  - added warning description regarding terminated objects to `get` long help message
  - added printing of warning message in case of `get pods` if there are hidden pods
Fixes kubernetes#22986

Automatic merge from submit-queue

Added warning msg for `kubectl get`

- added warning description regarding terminated pods to `get` long help message
  - added printing of warning message in case of `get pods` if there are hidden pods

Fixes #22986  (initiall PR and discussion are here #26417)

## **Output examples:**
### # kubectl get pods
```
NAME                       READY     STATUS             RESTARTS   AGE
dapi-test-pod1             0/1       Terminating        0          22h
liveness-http              0/1       CrashLoopBackOff   11245      22d
ubuntu1-1206318548-oh9tc   0/1       CrashLoopBackOff   2336       8d
  info: 1 completed object(s) was(were) not shown in pods list. Pass --show-all to see all objects.

```

### #  kubectl get pods,namespaces
```
NAME                          READY     STATUS             RESTARTS   AGE
po/dapi-test-pod1             0/1       Terminating        0          22h
po/liveness-http              1/1       Running            11242      22d
po/ubuntu1-1206318548-oh9tc   0/1       CrashLoopBackOff   2335       8d
 info: 1 completed object(s) was(were) not shown in pods list. Pass --show-all to see all objects.

NAME             STATUS    AGE
ns/default       Active    89d
ns/kube-system   Active    41d
```

### # kubectl get pods -a
```
NAME                       READY     STATUS             RESTARTS   AGE
busybox                    0/1       Error              0          27d
dapi-test-pod1             0/1       Terminating        0          22h
liveness-http              0/1       CrashLoopBackOff   11245      22d
ubuntu1-1206318548-oh9tc   0/1       CrashLoopBackOff   2336       8d
```

### # kubectl get -h
```
Display one or many resources.

Possible resource types include (case insensitive): pods (aka 'po'), services (aka 'svc'), deployments (aka 'deploy'),
replicasets (aka 'rs'), replicationcontrollers (aka 'rc'), nodes (aka 'no'), events (aka 'ev'), limitranges (aka 'limits'),
persistentvolumes (aka 'pv'), persistentvolumeclaims (aka 'pvc'), resourcequotas (aka 'quota'), namespaces (aka 'ns'),
serviceaccounts (aka 'sa'), ingresses (aka 'ing'), horizontalpodautoscalers (aka 'hpa'), daemonsets (aka 'ds'), configmaps (aka 'cm'),
componentstatuses (aka 'cs), endpoints (aka 'ep'), petsets (alpha feature, may be unstable) and secrets.

This command will hide resources that have completed. For instance, pods that are in the Succeeded or Failed phases.
You can see the full results for any resource by providing the '--show-all' flag.

By specifying the output as 'template' and providing a Go template as the value
of the --template flag, you can filter the attributes of the fetched resource(s).

Examples:

.........
````