[BUGFIX] Fix the asset paths in single HTMl

And add an integration test for single HTML.

It was until now not possible testing it.

There are still open issues with single HTMl, but I would suggest to solve them in follow-ups.

- TYPO3-Documentation/render-guides#238
- TYPO3-Documentation/render-guides#239

Resolves TYPO3-Documentation/render-guides#233

resources/template/structure/singlepage.html.twig

@@ -3,7 +3,9 @@
 {% block body %}
     <!-- content start -->
     {% for document in documents -%}
-        {{ renderNode(document) }}
+        <article>
+            {{ renderNode(document) }}
+        </article>
     {%~ endfor -%}
     <!-- content end -->
 {% endblock %}

src/Twig/TwigExtension.php

@@ -103,6 +103,7 @@ public function getCurrentFilename(array $context): string
      */
     public function getRelativePath(array $context, string $path): string
     {
+        $renderContext = $this->getRenderContext($context);
         if ($this->typo3AzureEdgeURI !== '') {
             // CI (GitHub Actions) gets special treatment, then we use a fixed URI for assets.
             // TODO: Fixate the "_resources" string as a class/config constant, not hardcoded