PURPOSE
Rename fields on mail_thread and wizard: ``no_auto_thread`` should be replaced
to ``reply_to_force_new`` to ease understanding and be prefixed by reply_to.
SPECIFICATIONS
For better understanding, this commit renames ``no_auto_thread`` field of
``mail.message`` model to ``reply_to_force_new``, to indicate that if the
field is checked (☑) replies should check gateway alias rules instead of
updating mailed threads.
It is also more coherent with reply_to namespacing used in various mail models
(notably new composer fields and ``reply_to_mode`` of mass mailing and mail
composer models)
LINKS
Task ID-2117639
COM PR odoo/odoo#40931
ENT PR odoo/enterprise#17941
UPG PR odoo/upgrade#2419