[FIX] sale: fix down payment missing tax and product UoM

In the sales modules, set a down payment product with a different UoM
than the default one.

If you create an invoice, select the down payment option, click on
create and view.

Before this commit:

    - The down payment tax & UoM are not on the invoice line

After this commit:

    - They are on the invoice line, like in V12

OPW-2086146

closes odoo/odoo#39557

Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>

addons/sale/wizard/sale_make_invoice_advance.py

@@ -99,6 +99,8 @@ class SaleAdvancePaymentInv(models.TransientModel):
                 'price_unit': amount,
                 'quantity': 1.0,
                 'product_id': self.product_id.id,
+                'product_uom_id': so_line.product_uom.id,
+                'tax_ids': [(6, 0, so_line.tax_id.ids)],
                 'sale_line_ids': [(6, 0, [so_line.id])],
                 'analytic_tag_ids': [(6, 0, so_line.analytic_tag_ids.ids)],
                 'analytic_account_id': order.analytic_account_id.id or False,