[FIX] purchase: vendor currency
[FIX] purchase: vendor currency

When defined, the vendor currency should be the default on vendor bills.

Fixes #13017
Closes #13016
opw-685016

Elico-Corp/odoo_OCB,hip-odoo/odoo,microcom/odoo,microcom/odoo,ygol/odoo,hip-odoo/odoo,bplancher/odoo,ygol/odoo,bplancher/odoo,storm-computers/odoo,ygol/odoo,dfang/odoo,laslabs/odoo,laslabs/odoo,ygol/odoo,bplancher/odoo,microcom/odoo,laslabs/odoo,dfang/odoo,microcom/odoo,Elico-Corp/odoo_OCB,hip-odoo/odoo,laslabs/odoo,Elico-Corp/odoo_OCB,laslabs/odoo,Elico-Corp/odoo_OCB,ygol/odoo,hip-odoo/odoo,hip-odoo/odoo,storm-computers/odoo,bplancher/odoo,dfang/odoo,dfang/odoo,bplancher/odoo,laslabs/odoo,bplancher/odoo,storm-computers/odoo,storm-computers/odoo,dfang/odoo,ygol/odoo,ygol/odoo,storm-computers/odoo,hip-odoo/odoo,dfang/odoo,Elico-Corp/odoo_OCB,storm-computers/odoo,microcom/odoo,Elico-Corp/odoo_OCB,microcom/odoo