Additional tweaks for bootstrap5 support

btn-default -> btn-secondary
use mb-3 to add margin to bottom of input-groups
use $.modal('show') to show modals
use bi bi-trash icon (font-awesome doesn't seem to be included with bs5
data-bs-dismiss on the modal close buttons
put recheck templates in container divs
add input-group-text class to addon icons for input fields

mfa/templates/select_mfa_method.html

@@ -2,6 +2,7 @@
 {% block content %}
     <br/>
 <br/>
+<div class='container'>
 <div class="row">
 
 <div class="col-sm-10 col-sm-offset-1 col-xs-12 col-md-10 col-md-offset-1 col-lg-8 col-lg-offset-2">
@@ -24,6 +25,8 @@
           </ul>
       </div>
 </div>
+</div>
+
 </div>
 </div>
 {% endblock %}