How to use for Brazilian electronic invoicing (NFe)

This is still a work in progress but so far:

```
export XSDATA_SCHEMA=nfe
export XSDATA_VERSION=40
export XSDATA_SKIP='^ICMS.ICMS\d+|^ICMS.ICMSSN\d+'
xsdata xsdata schemas/nfe/v4_00 --output odoo
```

(how to download schemas can be found here https://github.com/akretion/nfelib#gerir-a-lib-novamente--processo-de-release)