storage: stop using deprecated io/ioutil

This replaces deprecated ioutil variables and functions as follows:

* ioutil.ReadDir -> os.ReadDir
* ioutil.ReadFile -> os.ReadFile
* ioutil.TempDir -> os.MkdirTemp
* ioutil.TempFile -> os.CreateTemp
* ioutil.WriteFile -> os.WriteFile

The ReadDir conversion involves an API change, the replacement
function returns a slice of fs.DirEntry instead of fs.FileInfo.
Where appropriate, the surrounding code has been adjusted; mostly,
that means using DirEntry.Type() instead of FileInfo.Mode().
Applying this change to the IoUtil interface would mean changing its
API, so this is left for later.

Signed-off-by: Stephen Kitt <skitt@redhat.com>

pkg/volume/util/hostutil/hostutil_linux_test.go

@@ -20,7 +20,6 @@ limitations under the License.
 package hostutil
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
@@ -193,12 +192,12 @@ func TestGetSELinuxSupport(t *testing.T) {
 }
 
 func writeFile(content string) (string, string, error) {
-	tempDir, err := ioutil.TempDir("", "mounter_shared_test")
+	tempDir, err := os.MkdirTemp("", "mounter_shared_test")
 	if err != nil {
 		return "", "", err
 	}
 	filename := filepath.Join(tempDir, "mountinfo")
-	err = ioutil.WriteFile(filename, []byte(content), 0600)
+	err = os.WriteFile(filename, []byte(content), 0600)
 	if err != nil {
 		os.RemoveAll(tempDir)
 		return "", "", err