MDL-69002 core_badges: move backpack validation to a separate page

Instead of running the site backpack validation every time badges/backpacks.php
page is loaded, an action button has been added to the backpacks with OB set
to 2.0 to let admins running manually this verification when needed.

badges/backpacks.php

@@ -80,6 +80,14 @@ if ($action == 'edit') {
     echo $output->heading(get_string('managebackpacks', 'badges'));
 
     $form->display();
+} else if ($action == 'test') {
+    // If no backpack has been selected, there isn't anything to test.
+    if (empty($id)) {
+        redirect($url);
+    }
+
+    echo $OUTPUT->header();
+    echo $output->render_test_backpack_result($id);
 } else {
     echo $OUTPUT->header();
     echo $output->heading(get_string('managebackpacks', 'badges'));

badges/classes/output/external_backpacks_page.php

@@ -72,11 +72,11 @@ class external_backpacks_page implements \renderable {
             } else {
                 $backpack->canedit = false;
             }
+            $backpack->cantest = ($backpack->apiversion == OPEN_BADGES_V2);
             $backpack->iscurrent = ($backpack->id == $CFG->badges_site_backpack);
 
             $data->backpacks[] = $backpack;
         }
-        $data->warning = badges_verify_site_backpack();
 
         return $data;
     }

badges/templates/external_backpacks_page.mustache

@@ -25,9 +25,8 @@
     Example context (json):
     {
         "backpacks": [
-            {"backpackweburl": "http://localhost/", "sitebackpack": true, "canedit": false}
-        ],
-        "warning": "<span class='text-warning'>Could not login</span>"
+            {"backpackweburl": "http://localhost/", "sitebackpack": true, "canedit": false, "cantest": true}
+        ]
     }
 }}
 
@@ -59,9 +58,11 @@
                     {{#pix}}t/delete, core,{{#str}}delete{{/str}}{{/pix}}
                 </a>
             {{/iscurrent}}
+            {{#cantest}}
+                <a href="{{baseurl}}?id={{id}}&action=test">{{#pix}}t/check, core,{{#str}}testsettings, core_badges{{/str}}{{/pix}}</a>
+            {{/cantest}}
             </td>
         </tr>
         {{/backpacks}}
     </tbody>
-</table>
-{{{warning}}}
+</table>