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>

lang/en/badges.php

@@ -552,6 +552,7 @@ $string['targetframework_help'] = 'The name of the external skill or standard fr
 $string['targetcode'] = 'Code';
 $string['targetcode_help'] = 'A unique string identifier for referencing the external skill or standard within its framework.';
 $string['testbackpack'] = 'Test backpack \'{$a}\'';
+$string['testsettings'] = 'Test settings';
 $string['type'] = 'Type';
 $string['variablesubstitution'] = 'Variable substitution in messages.';
 $string['variablesubstitution_help'] = 'In a badge message, certain variables can be inserted into the subject and/or body of a message so that they will be replaced with real values when the message is sent. The variables should be inserted into the text exactly as they are shown below. The following variables can be used: