This commits add a signature to the website_form.
The purpose of this modification is to allow the controllers to be
able to verify that the form was originally generated from the view.
This prevent the end user to submit arbitrary values to the website_form
controller.
In this commit, email_cc and email_bcc are treated as the same fied as
it holds the same function
This does not offer protection against submission replay. Previous versions
of the form are not invalidated by editing the view.
If one need to completely reset that protection and invalidate the
previously generated website_form, the only solution is currently to
change the database secret.
closesodoo/odoo#139701
Signed-off-by: Vranckx Florian (flvr) <flvr@odoo.com>