Don't flash the menu button on desktop screens

The button flashed briefly when loading the page. This was even more
obvious when using devices with slow internet connections.

Using CSS instead of JavaScript to hide the menu solves the issue, since
styles are loaded before scripts.

app/assets/stylesheets/layout/responsive_menu.scss

@@ -1,4 +1,8 @@
 [data-responsive-toggle=responsive_menu] {
+  @include breakpoint(medium) {
+    display: none;
+  }
+
   .menu-button {
     border: 1px solid;
     border-radius: $button-radius;

app/components/layout/responsive_menu_component.html.erb

@@ -1,4 +1,4 @@
-<span data-responsive-toggle="responsive_menu" data-hide-for="medium">
+<span data-responsive-toggle="responsive_menu">
   <button type="button" class="menu-button" data-toggle>
     <span class="menu-icon"></span>
     <%= t("application.menu") %>