Add HTML and ZIP file to make the result section better

Via this MR we introduce an HTML page and ZIP file to make the way of getting access to the produced data and understanding the directory structure of plugin output easier

example: https://www-regiklim.dkrz.de/history/6371/results/

pet-wrapper-api.py

@@ -194,6 +194,10 @@ class PET(plugin.PluginAbstract):
         return file_dict
 
     def prepare_html_output(self, path_output):
+        """
+        Prepare the HTML output for the plugin in 
+        the result section.
+        """
         result = subprocess.run(
             ["ls", "-la", path_output], capture_output=True, text=True
         )