[IMP] web_pdf_viewer: pdf viewer not open in SO invoice when press on print

As well as need to update class name base on recently update back-end new look.
Problem is globally need to update class name as well as proper selector to archived PDF report open in <code>&lt;iframe&gt;</code> element.

<b>Task</b> : https://www.odoo.com/web#id=10110&view_type=form&model=project.task&menu_id=3942&action=327
<b>Pad</b> : https://pad.odoo.com/p/r.CPefQmgrn2URFXQq