**[FIX] round_per_line: Fix payment CFDI rounding issues**

- 'base' * 'tasa_o_cuota' must give 'importe' with 0.01 rounding error allowed.
Suppose an invoice of 5 * 0.47 with 16% tax. Each line gives a tax amount of 0.08 so 0.40 for the whole invoice.
However, 5 * 0.47 = 2.35 and 2.35 * 0.16 = 0.38 so the constraint is failing.
- 'base' + 'importe' must be exactly equal to the part that is actually paid.
Using the same example, we need to report 2.35 + 0.40 = 2.75

**[FIX] round_globally: Manage round globally**

Before, the results given in case of round_globally was the same as round_per_line.
Suppose an invoice of 5 * 0.47 with 16% tax. We were sending a tax detail of
0.47 * 0.16 ~= 0.08 for each line, so 0.40 for the whole invoice.
However, in case of round globally, the total tax is 5 * 0.47 * 0.16 ~= 0.38.
The invoice was incorrectly reported as an invoice of 2.75 instead of 2.73.

To fix that, the base/tax amount per line are now given using 6 decimals.

**[FIX] Deterministic invoices's order in payment CFDI**

Before generating a payment CFDI, make sure the invoices are sorted in order to
avoid a not deterministic xml.

**[FIX] Rounding of TipoCambio**

On the xml, the rate to switch from the invoice to payment rate is rounded to 6 decimals.
By consistency, we need to use the same number of decimals during the computation to avoid
the xml to be rejected. For example:

With an MX company setup
USD Exchange rate:
  - Yesterday 17.187
  - Today 17.0357
Create an invoice with:
  - date: yesterday, quantity: 200, unit price: 7.34 USD, tax: 16%
Confirm and Send the invoice
Register the payment with today date
Open the payment and force cfdi
SAT Validation will return an error:
'''
Code : CRP20204 Message : El valor del campo TotalTrasladosBaseIVA16
no es igual al redondeo de la suma del resultado de multiplicar cada
uno de los importes de los atributos BaseP de los impuestos trasladados
registrados en el elemento TrasladoP donde los atributos contengan en
ImpuestoP el valor IVA, en TipoFactorP el valor Tasa y en TasaOCuotaP
el valor 0.160000, por el valor registrado en el atributo TipoCambioP
de cada nodo Pago.
'''

opw-3775099

**[FIX] Rounding of TotalTrasladosBaseIVA16**

- Have an MX company setup
- USD Exchange rate:
  - Yesterday 16.9912
  - Today 17.068
- Create two invoices as follows:
  1) date yesterday, qty 68.25, unit price 68 USD, tax 16%, total 5383.56 USD
  2) date yesterday, qty 24.00, unit price 68 USD, tax 16%, total 1893.12 USD
Confirm and Send the two invoices
In invoices list view, select both and register payment
Select 'Group Payments'
Open one of the invoices, and press "Update Payments"
In CFDI Tab Force cfdi for the payment

Issue: Cfdi validation return an error
"""
Code : CRP20204 Message : El valor del campo TotalTrasladosBaseIVA16 no es igual
al redondeo de la suma del resultado de multiplicar cada uno de los importes de
los atributos BaseP de los impuestos trasladados registrados en el elemento TrasladoP
donde los atributos contengan en ImpuestoP el valor IVA, en TipoFactorP el valor
Tasa y en TasaOCuotaP el valor 0.160000, por el valor registrado en el atributo
TipoCambioP de cada nodo Pago.
"""

opw-3775099

Forward-Port-Of: odoo/enterprise#60025