[8.0][mass_mailing][FIX]

* Rename `mailing_type` into `mailing model`
* Allow to reply into document that inherit from `mail.thread`
* Add missing fields when creating a new `mail mass_mailing` from `mail.compose.message`
* Repair sql request
Still doesn't agree with the change. The partner profile is effectively inheriting from mail.thread and therefore accepts incoming emails, but we think it should stay internal, and therefore keeping the warning seems necessary for us.