feat: add mail_outbound_static

Transactional mail servers will reject sending mails on behalf of third-party domains that are not owned (neither configured) by us.

This happens when someone replies to an Odoo sent mail: Odoo tries to notify followers by re-sending the mail received with the original From header.

In order to avoid those rejects, this module will check if the domain is in a white list and if not, it will replace the header to a configured email address.