Merge pull request #39038 from ncdc/fix-kubectl-get-list

Automatic merge from submit-queue

Fix kubectl get -f <file> -o <nondefault printer> so it prints all items in the file

**What this PR does / why we need it**: Fix kubectl get -f <file> -o <nondefault printer> so it prints all the objects in the file, instead of just the first one. Also add a test for this feature.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #38907 

**Special notes for your reviewer**:

**Release note**:

```release-note
```

cc @AdoHe @deads2k @liggitt @fabianofranz @kubernetes/kubectl @kubernetes/sig-cli-misc

pkg/kubectl/cmd/label.go

@@ -187,7 +187,7 @@ func (o *LabelOptions) RunLabel(f cmdutil.Factory, cmd *cobra.Command) error {
 			Latest()
 	}
 	one := false
-	r := b.Do().IntoSingular(&one)
+	r := b.Do().IntoSingleItemImplied(&one)
 	if err := r.Err(); err != nil {
 		return err
 	}