- Simple VAT error message when an error must be shown
- Always clean vies_passed field when check_vat is called
[FIX] tests
[FIX] Contributor emails
[FIX] Change _build_vat_error_message to _construct_constraint_msg from cherry-pick
[FIX] Remove api.model and put self.ensure_one()
* base_vat_optional_vies: Fix pass lower country code in _split_vat function to find parent function check_vat_'xx' instead of check_vat_'XX'
* base_vat_optional_vies: Convert to upper when write NIF into database