Merge pull request #38445 from brendandburns/configmap2

Automatic merge from submit-queue (batch tested with PRs 38445, 40292)

Add the ability to edit fields within a config map.

Addresses part of https://github.com/kubernetes/kubernetes/issues/36222

Example command:

```console
$ kubectl edit configmap foo --config-map-data=bar
```

Will open the data element named `bar` in the `ConfigMap` named `foo` in `$EDITOR`, the edited contents are then updated back to the config map.

@kubernetes/sig-cli 

```release-note
Add a special purpose tool for editing individual fields in a ConfigMap with kubectl
```

pkg/kubectl/cmd/edit.go

@@ -101,12 +101,20 @@ func NewCmdEdit(f cmdutil.Factory, out, errOut io.Writer) *cobra.Command {
 		Long:    editLong,
 		Example: fmt.Sprintf(editExample),
 		Run: func(cmd *cobra.Command, args []string) {
+			args = append([]string{"configmap"}, args...)
 			err := RunEdit(f, out, errOut, cmd, args, options)
 			cmdutil.CheckErr(err)
 		},
 		ValidArgs:  validArgs,
 		ArgAliases: argAliases,
 	}
+	addEditFlags(cmd, options)
+
+	cmd.AddCommand(NewCmdEditConfigMap(f, out, errOut))
+	return cmd
+}
+
+func addEditFlags(cmd *cobra.Command, options *resource.FilenameOptions) {
 	usage := "to use to edit the resource"
 	cmdutil.AddFilenameOptionFlags(cmd, options, usage)
 	cmdutil.AddValidateFlags(cmd)
@@ -116,7 +124,6 @@ func NewCmdEdit(f cmdutil.Factory, out, errOut io.Writer) *cobra.Command {
 	cmdutil.AddApplyAnnotationFlags(cmd)
 	cmdutil.AddRecordFlag(cmd)
 	cmdutil.AddInclude3rdPartyFlags(cmd)
-	return cmd
 }
 
 func RunEdit(f cmdutil.Factory, out, errOut io.Writer, cmd *cobra.Command, args []string, options *resource.FilenameOptions) error {