Snailmail holds an abstract model 'snailmail.confirm' that implements some
kind of generic confirmation flow. It is nowadays used in a single case
that is the 'snailmail.confirm.invoice' wizard that inherits of it in
snailmail_account.
In this commit we remove the base abstract model, as it is defined once
and does not really add value. This kind of generic model actually adds
more noise than solves issues.
The invoice confirmation wizard is now completely defined in snailmail
account bridge, easing understanding of models.
Task-3046371 (Mail: Better Language Support in Composer)
closesodoo/odoo#111901
Related: odoo/upgrade#4299
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>