Add EC sales list and VAT customer
With #6734 (closed), the intracommunity taxes must be updated to get the EC sales list code using
https://finances.belgium.be/sites/default/files/downloads/165-723-formulaire-2016.pdf
https://finances.belgium.be/sites/default/files/downloads/165-723-directives-2016.pdf
But it is not enough for Belgium, this listing is also required: https://finances.belgium.be/sites/default/files/downloads/165-725-formulaire-2016.pdf