Currently when using the composer to create a mass mailing emails are sent
directly, unless scheduled date is in the future.
With this commit it is now controllable through a field like what has been
done on SMS composer. Its default behavior is the same as before
* posting on a monorecord: force send notification emails;
* posting on multirecords: use the queue (force_send=False parameter given
to message_post and propagated to _notify_thread);
* mass mailing: use force send to send emails directly;
Usage of mail_notify_force_send context key is also removed when possible
as it is a standard parameter of posting API.
Task-3132710 (Mail: Configurable composer)
Part-of: odoo/odoo#99482
Thibault Delavallée
360d9ce201