Feat 4612 real time metrics for kube nodes (#4708)

* feat(k8s/node): display realtime node metrics GH#4612

* feat(k8s): show observation timestamp instead of real timestamp GH#4612

Co-authored-by: Simon Meng <simon.meng@portainer.io>

app/kubernetes/components/datatables/nodes-datatable/nodesDatatable.html

@@ -107,6 +107,9 @@
                   <i class="fa fa-sort-alpha-up" aria-hidden="true" ng-if="$ctrl.state.orderBy === 'IPAddress' && $ctrl.state.reverseOrder"></i>
                 </a>
               </th>
+              <th ng-if="$ctrl.useServerMetrics">
+                Actions
+              </th>
             </tr>
           </thead>
           <tbody>
@@ -128,6 +131,9 @@
               <td>{{ item.Memory | humansize }}</td>
               <td>{{ item.Version }}</td>
               <td>{{ item.IPAddress }}</td>
+              <td ng-if="$ctrl.useServerMetrics">
+                <a ui-sref="kubernetes.cluster.node.stats({ name: item.Name })" style="cursor: pointer;"> <i class="fa fa-chart-area" aria-hidden="true"></i> Stats </a>
+              </td>
             </tr>
             <tr ng-if="!$ctrl.dataset">
               <td colspan="7" class="text-center text-muted">Loading...</td>