MDL-57075 message: notification popover see all link

The "see all" link in the notification popover should link to the full
notifications page similar to how the "see all" link in the message
popover links to the messaging page.

lib/templates/popover_region.mustache

@@ -64,12 +64,14 @@
             {{> core/loading }}
         </div>
         {{$anchor}}
-            <a class="see-all-link"
-                href="{{{urls.seeall}}}">
-                <div class="popover-region-footer-container">
-                    <div class="popover-region-seeall-text">{{#str}} seeall, message {{/str}}</div>
-                </div>
-            </a>
+            {{#urls.seeall}}
+                <a class="see-all-link"
+                    href="{{{.}}}">
+                    <div class="popover-region-footer-container">
+                        <div class="popover-region-seeall-text">{{#str}} seeall, message {{/str}}</div>
+                    </div>
+                </a>
+            {{/urls.seeall}}
         {{/anchor}}
     </div>
 </div>

message/output/popup/lib.php

@@ -61,6 +61,7 @@ function message_popup_render_navbar_output(\renderer_base $renderer) {
         $context = [
             'userid' => $USER->id,
             'urls' => [
+                'seeall' => (new moodle_url('/message/output/popup/notifications.php'))->out(),
                 'preferences' => (new moodle_url('/message/notificationpreferences.php', ['userid' => $USER->id]))->out(),
             ],
         ];