Merge pull request #35805 from dgoodwin/token-mgmt

Automatic merge from submit-queue

Implement kubeadm bootstrap token management

Creates bootstrap tokens as secrets per the specification in #30707 

_WARNING_: These are not currently hooked up to the discovery service or the token it creates.

Still TODO:
- [x] delete tokens
- [x] merge with #35144 and adopt it's testing approach
- [x] determine if we want wholesale json output & templating like kubectl (we do not have an API object with the data we want here) may require a bit of plumbing.
- [x] allow specifying a token duration on the CLI
- [x] allow configuring the default token duration
- [x] hook up the initial token created during init

Sample output:

```
(root@centos1 ~) $ kubeadm token create
Running pre-flight checks
<cmd/token> Token secret created: f6dc69.c43e491752c4a0fd
(root@centos1 ~) $ kubeadm token create
Running pre-flight checks
<cmd/token> Token secret created: 8fad2f.e7b78c8a5f7c7b9a
(root@centos1 ~) $ kubeadm token list  
Running pre-flight checks
ID        TOKEN                     EXPIRATION
44d805    44d805.a4e78b6cf6435e33   23h
4f65bb    4f65bb.d006a3c7a0e428c9   23h
6a086e    6a086e.2ff99f0823236b5b   23h
8fad2f    8fad2f.e7b78c8a5f7c7b9a   23h
f6dc69    f6dc69.c43e491752c4a0fd   23h
f81653    f81653.9ab82a2926c7e985   23h
```

pkg/kubectl/resource_printer.go

@@ -657,7 +657,7 @@ func formatEndpoints(endpoints *api.Endpoints, ports sets.String) string {
 	return ret
 }
 
-func shortHumanDuration(d time.Duration) string {
+func ShortHumanDuration(d time.Duration) string {
 	// Allow deviation no more than 2 seconds(excluded) to tolerate machine time
 	// inconsistence, it can be considered as almost now.
 	if seconds := int(d.Seconds()); seconds < -1 {
@@ -682,7 +682,7 @@ func translateTimestamp(timestamp metav1.Time) string {
 	if timestamp.IsZero() {
 		return "<unknown>"
 	}
-	return shortHumanDuration(time.Now().Sub(timestamp.Time))
+	return ShortHumanDuration(time.Now().Sub(timestamp.Time))
 }
 
 func printPodBase(pod *api.Pod, w io.Writer, options PrintOptions) error {