(js) Add "Move To" option for selected messages

Fixes #3477

UI/WebServerResources/scss/components/menu/menu.scss

@@ -20,4 +20,26 @@ md-sidenav {
       }
     }
   }
-}
+}
+
+
+// submenu hack
+// See https://github.com/angular/material/issues/6096
+md-menu-content {
+  .md-menu {
+    @extend md-menu-item;
+    padding: 0;
+    > .md-button {
+      line-height: $menu-item-height;
+      &:after {
+        display: block;
+        content: '\25BC';
+        position: absolute;
+        top: 0px;
+        speak: none;
+        transform: rotate(270deg) scaleY(0.45) scaleX(0.9);
+        right: 2 * $baseline-grid;
+      }
+    }
+  }
+}