[IMP] website_sale: perform small UX improvements
[IMP] website_sale: perform small UX improvements

 * Display 'order confirmed' only if it is actually the case;
 * Display uom only if those are managed;

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo