add support for extra actions in 'sandwich' menu (#14830)

The menu should be a list with "extra-actions-menu" class and the
toggler a link with class "extra-actions-menu-opener".

For example:

<a class="extra-actions-menu-opener"></a>
<ul class="extra-actions-menu">
  ...
</ul>

gadjo/static/css/gadjo.scss

@@ -865,6 +865,59 @@ ul.apps li.icon-announces a:hover { background-image: url(icons/announces.large-
 	}
 }
 
+#appbar {
+	.extra-actions-menu-opener {
+		border: none;
+		&::before {
+			cursor: pointer;
+			content: "\f142"; /* ellipsis-v */
+			font-family: FontAwesome;
+			font-size: 140%;
+			padding: 2px 1ex;
+			margin-right: -0.5ex;
+			border: 1px solid transparent;
+			border-bottom: 0;
+			position: relative;
+			z-index: 200;
+			top: 2px;
+		}
+		&.open::before {
+			background: #fafafa;
+			border-color: #d0d0d0;
+		}
+	}
+	.extra-actions-menu {
+		background: white;
+		padding: 0px;
+		list-style: none;
+		position: absolute;
+		right: -7px;
+		margin-top: -24px;
+		border: 1px solid #d0d0d0;
+		background: #fafafa;
+		box-shadow: 0px 1px 1px 2px rgba(0, 0, 0, 0.04);
+		z-index: 100;
+		display: none;
+		min-width: 12em;
+		&.open {
+			display: block;
+		}
+		li {
+			margin: 0;
+			a {
+				float: none;
+				display: block;
+				margin: 0;
+				padding: 5px 10px;
+				border: none;
+				&:hover {
+					background: #ccc;
+				}
+			}
+		}
+	}
+}
+
 @import 'grid';
 @import 'jqueryui';
 @import 'forms';

gadjo/static/js/gadjo.js

@@ -324,4 +324,10 @@ var gadjo_js = gadjo_js || {};
         $(this).prepend(elem);
       });
     });
+    $(function() {
+        $('a.extra-actions-menu-opener').on('click', function() {
+            $(this).toggleClass('open');
+            $('.extra-actions-menu').toggleClass('open');
+        });
+    });
 })();