ISTWCMS-4847: adding preprocess to main content area to add classes for 404...

ISTWCMS-4847: adding preprocess to main content area to add classes for 404 pages and cleaning up template for main content

templates/regions/region--content.html.twig

-{#
-/**
- * @file
- * Theme override to display a region.
- *
- * Available variables:
- * - content: The content for this region, typically blocks.
- * - attributes: HTML attributes for the region div.
- * - region: The name of the region variable as defined in the theme's
- *   .info.yml file.
- *
- * @see template_preprocess_region()
- */
-#}
-{% embed '@layouts/content/content.twig' with {
-  'classes': classes
-}%}
-
-  {% block content %}
-    {{ content }}
-  {% endblock %}
-
-{% endembed %}
+{#
+/**
+ * @file
+ * Theme override to display a region.
+ *
+ * Available variables:
+ * - content: The content for this region, typically blocks.
+ * - attributes: HTML attributes for the region div.
+ * - region: The name of the region variable as defined in the theme's
+ *   .info.yml file.
+ *
+ * @see template_preprocess_region()
+ */
+#}
+{% embed '@layouts/content/content.twig' with {
+  'classes': classes
+}%}
+
+  {% block content %}
+    {{ content }}
+  {% endblock %}
+
+{% endembed %}