Fix sidebar popup scrolling

jet/static/jet/css/_sidebar.scss

@@ -392,6 +392,7 @@
     color: $sidebar-popup-text-color;
     background-color: $sidebar-popup-background-color;
     overflow-y: auto;
+    -webkit-overflow-scrolling: touch;
 
     @include for-mobile {
       min-width: 280px;

jet/templates/admin/base.html

@@ -247,7 +247,7 @@
 
             {% if app_list and not SIDE_MENU_COMPACT %}
                 <div class="sidebar-popup-container">
-                    <div class="sidebar-popup">
+                    <div class="sidebar-popup scrollable">
                         <a href="#" class="sidebar-close popup sidebar-back">
                             <span class="sidebar-close-icon icon-arrow-left"></span>
                         </a>