Archive tool: allow download for all documents of several tasks/gta

The data archiving for the type "task module" is extended. Using checkboxes, several task modules can be selected simultaneously and all documents can be downloaded collectively.

If possible, the result is only one ZIP file. This file contains the folders of the various selected task modules - and in it the contents as before.

FX Internal: book to https://office.bexio.com/index.php/pr_project/listMonitoring/projectId/126