Moved all flag code from `staging/src/k8s.io/apiserver/pkg/util/[flag|globalflag]` to `component-base/cli/[flag|globalflag]` except for the term function because of unwanted dependencies.
Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Correct typos and missing word in help text
**What this PR does / why we need it**:
Corrects a grammatical/readability error in the help output.
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use subtest for table units (pkg/kubectl)
**What this PR does / why we need it**:
Go 1.7 added the subtest feature which can make table-driven tests much easier to run and debug. Many table-driven tests in pkg/kubectl are not using this feature.
/kind cleanup
/area kubectl
Further reading: [Using Subtests and Sub-benchmarks](https://blog.golang.org/subtests)
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #
**Special notes for your reviewer**:
**Release note**:
```release-note
NONE
```
Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
fix kubectl -o
Fix kubectl -o error message:
Before this change:
```
kubectl get pods -o foo
error: unable to match a printer suitable for the output format "" and the options specified: &get.PrintFlags{JSONYamlPrintFlags:(*genericclioptions.JSONYamlPrintFlags)(0x23aa610), NamePrintFlags:(*genericclioptions.NamePrintFlags)(0xc42058b4e0), TemplateFlags:(*printers.KubeTemplatePrintFlags)(0xc4206765e0), CustomColumnsFlags:(*printers.CustomColumnsPrintFlags)(0xc420676620), HumanReadableFlags:(*get.HumanPrintFlags)(0xc4204eb180), NoHeaders:(*bool)(0xc4206fefbc), OutputFormat:(*string)(0xc42058b4d0)}
```
After this change:
```
Kubectl get pods -o foo
error: unable to match a printer suitable for the output format "foo", allowed formats are: json,yaml,name,template,go-template,go-template-file,templatefile,jsonpath,jsonpath-file,custom-columns-file,custom-columns,wide
```
**What this PR does / why we need it**:
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #
**Special notes for your reviewer**:
**Release note**:
```release-note
kubectl will list all allowed print formats when an invalid format is passed.
```
Fix kubectl -o error message:
Before this change:
```shell
kubectl get pods -o foo
error: unable to match a printer suitable for the output format "" and the options specified: &get.PrintFlags{JSONYamlPrintFlags:(*genericclioptions.JSONYamlPrintFlags)(0x23aa610), NamePrintFlags:(*genericclioptions.NamePrintFlags)(0xc42058b4e0), TemplateFlags:(*printers.KubeTemplatePrintFlags)(0xc4206765e0), CustomColumnsFlags:(*printers.CustomColumnsPrintFlags)(0xc420676620), HumanReadableFlags:(*get.HumanPrintFlags)(0xc4204eb180), NoHeaders:(*bool)(0xc4206fefbc), OutputFormat:(*string)(0xc42058b4d0)}
```
After this change:
```shell
Kubectl get pods -o foo
error: unable to match a printer suitable for the output format "aaa", allowed formats are: custom-columns,custom-columns-file,go-template,go-template-file,json,jsonpath,jsonpath-file,name,template,templatefile,wide,yaml
```
Automatic merge from submit-queue (batch tested with PRs 63291, 63490, 60445, 63507, 63524). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
clean unused variables
**What this PR does / why we need it**:
clean unused variables on set.go
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #
**Special notes for your reviewer**:
**Release note**:
```release-note
NONE
```
Automatic merge from submit-queue (batch tested with PRs 59391, 58097, 60057, 60090). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
cleanup printers some more
This cleans up some more dead printer flags and unnecessary arguments for various methods. We're getting closer. Still need to clean up some ugly around `PrintSuccess` and then its time to start trimming layers.
@kubernetes/sig-cli-maintainers
```release-note
NONE
```
Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
update vendor spf13/cobra to enforce required flags
**What this PR does / why we need it**:
spf13/cobra#502 has enforced checking flags that marked as required, an error will be raised if unset.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*:fixes #54855
xref #48400fixeskubernetes/kubectl#121
**Special notes for your reviewer**:
/assign @liggitt @eparis
**Release note**:
```release-note
kubectl now enforces required flags at a more fundamental level
```
Ilya Dmitrichenko