Implement image previewing

I have tested this with png and jpeg/jpg which both work but most other image types should work as well.
![image](/attachments/25318577-d48c-4902-93b3-9adbb8b954e7)

Co-authored-by: Jan Klattenhoff <j.klattenhoff@neusta.de>
Reviewed-on: sites/file-explorer#12
Co-authored-by: jank1619 <jan@kjan.email>
Co-committed-by: jank1619 <jan@kjan.email>

templates/file.html.twig

@@ -15,7 +15,11 @@
         </a>
 
         <div class="mt-6 text-gray-700 overflow-auto max-h-96">
-            <p class="whitespace-pre-wrap leading-relaxed break-all text-balance">{{ file.content|raw }}</p>
+            {% if file.mimeType starts with 'image' %}
+                <img src="{{ path('serve_file', {filePath: file.name}) }}" alt="">
+            {% else %}
+                <p class="whitespace-pre-wrap leading-relaxed break-all text-balance">{{ file.content|raw }}</p>
+            {% endif %}
         </div>
     </div>
 {% endblock %}