The 'download' button should download *all* the attachments linked to
the move. Depending on the localization, an xml might be needed in
addition to the PDF (e.g. the CFDI and the signed PDF in Mexico).
To do that, we open a headless Send & Print wizard with only the
`download` checkbox set to True.
Secondly, do not show the 'Download' button in the portal view if no
official attachment is linked to the move (the print button still
appears).
task-3542881
Part-of: odoo/odoo#138206
Julien Van Roy
acca2f71ad