Show latest active device as last active on admin page

src/static/templates/admin/users.hbs

@@ -21,6 +21,8 @@
                             <div class="float-left">
                                 <strong>{{Name}}</strong>
                                 <span class="d-block">{{Email}}</span>
+                                <span class="d-block">Created at: {{created_at}}</span>
+                                <span class="d-block">Last active: {{last_active}}</span>
                                 <span class="d-block">
                                     {{#if TwoFactorEnabled}}
                                         <span class="badge badge-success mr-2" title="2FA is enabled">2FA</span>