Automatic merge from submit-queue
add linebreak between resource groups
**Release note**:
```release-note
release-note-none
```
Printing multiple groups via `kubectl get all` can produce output that is
hard to read in cases where there are a lot of resource types to display
/ some resource types contain varying column amounts.
This patch adds a linebreak above each group of resources only when
there is more than one group to display, and always omitting the
linebreak above the first group. This makes for slightly improved
output.
Linebreaks are printed to stderr, and honor the `--no-headers` option.
**Before**
```
$ kubectl get all
NAME READY STATUS RESTARTS AGE
po/database-1-u9m9l 1/1 Running 3 5d
po/idling-echo-1-9fmz6 2/2 Running 8 5d
po/idling-echo-1-gzb0v 2/2 Running 4 5d
NAME DESIRED CURRENT READY AGE
rc/database-1 1 1 1 6d
rc/idling-echo-1 2 2 2 6d
NAME CLUSTER-IP EXTERNAL-IP PORT(S)
AGE
svc/database 172.30.11.104 <none> 5434/TCP
6d
svc/frontend 172.30.196.217 <none> 5432/TCP
6d
svc/idling-echo 172.30.115.67 <none> 8675/TCP,3090/UDP
6d
svc/kubernetes 172.30.0.1 <none> 443/TCP,53/UDP,53/TCP
6d
svc/mynodeport 172.30.81.254 <nodes> 8080/TCP
5d
svc/mynodeport1 172.30.198.193 <nodes> 8080/TCP
5d
svc/mynodeport2 172.30.149.48 <nodes> 8080/TCP
5d
svc/mynodeport3 172.30.195.235 <nodes> 8080/TCP
5d
```
**After**
```
$ kubectl get all
NAME READY STATUS RESTARTS AGE
po/database-1-u9m9l 1/1 Running 3 5d
po/idling-echo-1-9fmz6 2/2 Running 8 5d
po/idling-echo-1-gzb0v 2/2 Running 4 5d
NAME DESIRED CURRENT READY AGE
rc/database-1 1 1 1 6d
rc/idling-echo-1 2 2 2 6d
NAME CLUSTER-IP EXTERNAL-IP PORT(S)
AGE
svc/database 172.30.11.104 <none> 5434/TCP
6d
svc/frontend 172.30.196.217 <none> 5432/TCP
6d
svc/idling-echo 172.30.115.67 <none> 8675/TCP,3090/UDP
6d
svc/kubernetes 172.30.0.1 <none> 443/TCP,53/UDP,53/TCP
6d
svc/mynodeport 172.30.81.254 <nodes> 8080/TCP
5d
svc/mynodeport1 172.30.198.193 <nodes> 8080/TCP
5d
svc/mynodeport2 172.30.149.48 <nodes> 8080/TCP
5d
svc/mynodeport3 172.30.195.235 <nodes> 8080/TCP
5d
```
cc @fabianofranz @liggitt
b840605197