[FIX] account_xunnel: modify the way of give a manual transaction its name to avoid concatenate bool and string

- Added the `.xml` extension to the datas created by the wizard that
  downloads the invoices from the SAT, this was done to make it
  compatible with the workflow of all l10n_mx_* apps.

- The python of the wizard used to save the connection was refactored, because the default
onchange, of the related field does not changed the original value, also we had security
problems, because we need to modify the connection token in the main company.
- The view of the wizard used to save the connection was improved:
    * connection token use password widget
    * the default footer and buttons were replaced to a new one to ensure the token saved
- The python of the wizard used to download the XML from SAT refactored to avoid
using related fields, due to security problems when trying to modify the last_sync_date
of the current company.
- The message error when the Credential creator is opened was improved, using the actual
error.

1. Avoid error with taxes on CFDI 3.2
2. In CFDI 3.2, other option to the currency name is ``NACIONAL``, now
   is supported this label in the currency.

vendor-bills

difference allowed between the amount in the XML and the invoice.

PS: This is already implemented in vendor-bills.

The attribute xmlns:schemaLocation is replaced
by xsi:schemaLocation for the correct import of the data

Recently a version of DeployV was released that turned some builds red.
This is because everything is being migrated to py3, losing backward compatibility with py2.

We use the current company instead  default company

- When attaching a customer invoice, it must not sign the xml or create
  a new one, it must associate the attachment that is uploaded and
  update the status (pac, sat) of the invoice.

When a CFDI has more decimals that Odoo, when you try to re-calculate
the taxes, an error is shown because the amounts could change.

```
Error: No se puede crear una entrada de diario no balanceada.. Ids: [209]

Diferencias débito - crédito: [0.08]
```

Now was fixed

Copies from:
https://git.vauxoo.com/vauxoo/vendor-bills/-/commit/e80fb05f57ae53b9b92a35175f539602aa76907a

[IMP] invoice_xunnel: Added to the Document Explorer the field of related_cfdi when an XML have a related CFDI

Manuel Gómez [Vauxoo] authored May 17, 2020 and Olar Alca [Vauxoo] committed May 21, 2020

New button to show invoices downloaded in sync with xunnel

[IMP]account_xunnel,invoice_xunnel: Added a message about the email with the invoices failed. Also added the config params to data with the server url

Manuel Gómez [Vauxoo] authored May 01, 2020 and Olar Alca [Vauxoo] committed May 05, 2020

The product list was extracted from the xml and displayed in the document viewer