In this commit we order fields more logically to ease reading and prepare
future modifications. We also rename the class and some field strings to
be more user friendly.
LINKS
Prepares Task ID 2238597 (clean notification models)
Prepares Task ID 2083854 (improve mass mailing technical flows)
PR #49891
Co-Authored-By: Rémy Voet <ryv@odoo.com>
Co-Authored-By: Thibault Delavallée <tde@odoo.com>