add resource handling before printing

Resources are currently filtered (in order to prevent printing) at print
time in their HumanReadablePrinter handlers. This design makes it not
possible to filter objects when they are printed using any other
printer, such as YAML, JSON, or the NamePrinter.

This patch removes any filters previously added at the printer level for
pods and adds a way to define resource-specific filters before they are
sent to a printer handler. A woking filter handler for pods has also
been
implemented.

Filters affect resources being printed through the HumanReadablePrinter,
YAML, JSON, and `--template` printers.

pkg/kubectl/cmd/cmd_test.go

@@ -749,16 +749,25 @@ func Example_printPodHideTerminated() {
 	}
 	cmd := NewCmdRun(f, os.Stdin, os.Stdout, os.Stderr)
 	podList := newAllPhasePodList()
-	mapper, _ := f.Object()
-	err := f.PrintObject(cmd, mapper, podList, os.Stdout)
-	if err != nil {
-		fmt.Printf("Unexpected error: %v", err)
+	// filter pods
+	filterFuncs := f.DefaultResourceFilterFunc()
+	filterOpts := f.DefaultResourceFilterOptions(cmd, false)
+	_, filteredPodList, errs := cmdutil.FilterResourceList(podList, filterFuncs, filterOpts)
+	if errs != nil {
+		fmt.Printf("Unexpected filter error: %v\n", errs)
+	}
+	for _, pod := range filteredPodList {
+		mapper, _ := f.Object()
+		err := f.PrintObject(cmd, mapper, pod, os.Stdout)
+		if err != nil {
+			fmt.Printf("Unexpected error: %v", err)
+		}
 	}
 	// Output:
 	// NAME      READY     STATUS    RESTARTS   AGE
 	// test1     1/2       Pending   6          10y
-	// test2     1/2       Running   6          10y
-	// test5     1/2       Unknown   6          10y
+	// test2     1/2       Running   6         10y
+	// test5     1/2       Unknown   6         10y
 }
 
 func Example_printPodShowAll() {