show filemanager button in app mounts section

dashboard/src/views/app.html

@@ -1079,6 +1079,7 @@
                   </select>
                 </td>
                 <td class="text-right no-wrap" style="vertical-align: middle">
+                  <a class="btn btn-xs btn-default" ng-href="{{ '/frontend/filemanager.html#/home/volume/' + mount.volume.id }}" target="_blank" uib-tooltip="{{ 'volumes.openFileManagerActionTooltip' | tr }}"><i class="fas fa-folder"></i></a>
                   <button class="btn btn-danger btn-xs" ng-click="storage.delMount($event, $index)"><i class="far fa-trash-alt"></i></button>
                 </td>
               </tr>