ISTWCMS-3664: adding stylings for layout builder

source/_patterns/03-layouts/layout/_layout.scss

+.layout {
+  .uw-contained-width {
+    @include uw-contained-width;
+  }
+}

source/_patterns/03-layouts/layout/layout.twig

+<div class="layout layout--{{ type }}">
+  <div {{ region_attributes.content.addClass('layout__region', 'layout__region--content', width) }}>
+    {% block content %}
+      Layout Region One Column Layout
+    {% endblock %}
+  </div>
+</div>