introduce new ServiceV2 API to handle guided restarts (#18826)

New API now verifies any hung disks before restart/stop,
provides a 'per node' break down of the restart/stop results.

Provides also how many blocked syscalls are present on the
drives and what users must do about them.

Adds options to do pre-flight checks to provide information
to the user regarding any hung disks. Provides 'force' option
to forcibly attempt a restart() even with waiting syscalls
on the drives.

cmd/admin-handlers_test.go

@@ -168,6 +168,7 @@ func testServiceSignalReceiver(cmd cmdType, t *testing.T) {
 func getServiceCmdRequest(cmd cmdType, cred auth.Credentials) (*http.Request, error) {
 	queryVal := url.Values{}
 	queryVal.Set("action", string(cmd.toServiceAction()))
+	queryVal.Set("type", "2")
 	resource := adminPathPrefix + adminAPIVersionPrefix + "/service?" + queryVal.Encode()
 	req, err := newTestRequest(http.MethodPost, resource, 0, nil)
 	if err != nil {
@@ -220,12 +221,18 @@ func testServicesCmdHandler(cmd cmdType, t *testing.T) {
 	rec := httptest.NewRecorder()
 	adminTestBed.router.ServeHTTP(rec, req)
 
+	resp, _ := io.ReadAll(rec.Body)
 	if rec.Code != http.StatusOK {
-		resp, _ := io.ReadAll(rec.Body)
 		t.Errorf("Expected to receive %d status code but received %d. Body (%s)",
 			http.StatusOK, rec.Code, string(resp))
 	}
 
+	result := &serviceResult{}
+	if err := json.Unmarshal(resp, result); err != nil {
+		t.Error(err)
+	}
+	_ = result
+
 	// Wait until testServiceSignalReceiver() called in a goroutine quits.
 	wg.Wait()
 }