Add a new optional parameter to handle processing files with more "specific" file formats:
file_ext— Custom file extension to use when searching for translation files (without leading dot). By default, the extension is inferred from the file_format value. However, for certain formats (e.g.,json_structured), the downloaded files may still have a generic extension (e.g.,.json). In such cases, this parameter allows specifying the correct extension manually to ensure proper file matching.