Feature: Mass award badge (#8694)

* UI: Mass grant a badge from the admin ui

* Send the uploaded CSV and badge ID to the backend

* Read the CSV and grant badge in batches

* UX: Communicate the result to the user

* Don't award if badge is disabled

* Create a 'send_notification' method to remove duplicated code, slightly shrink badge image. Replace router transition with href.

* Dynamically discover current route

app/assets/javascripts/admin/templates/badges-award.hbs

@@ -0,0 +1,22 @@
+{{#d-section class="award-badge"}}
+  <form class="form-horizontal">
+    <h1>{{i18n 'admin.badges.mass_award.title'}}</h1>
+    <div class='badge-preview'>
+      {{#if model}}
+        {{icon-or-image model}}
+        <span class="badge-display-name">{{model.name}}</span>
+      {{else}}
+        <span class='badge-placeholder'>{{I18n 'admin.badges.mass_award.no_badge_selected'}}</span>
+      {{/if}}
+    </div>
+    <div>
+      <h4>{{I18n 'admin.badges.mass_award.upload_csv'}}</h4>
+      <input type='file' id='massAwardCSVUpload' accept='.csv' />
+    </div>
+    {{d-button
+        class="btn-primary"
+        action=(action 'massAward')
+        disabled=saving
+        label="admin.badges.save"}}
+  </form>
+{{/d-section}}