[IMP] improve code for multi currency value in reporting view in sale, p...

...urchase, pos same like in invoice.

[IMP] Improve code for add multi currency rate in currency.

- Task: https://www.odoo.com/web?#id=9474&view_type=form&model=project.task&menu_id=3942&action=327
- Pad: https://pad.odoo.com/p/r.8hTOdNuFhMtUoy5x