[FIX] mail: fix sending failures email wizard

due to breaking changes in https://github.com/odoo/odoo/commit/bf32b22ce247c19fda94ded74e37f7c6120ce2c4
and especially the part:

"NOTE 1.  If the default_get within the onchange returns a value for
a field that is not in the view, we ignore it, and it won't be saved.
Before, that value was kept and sent upon save.  This change in behavior
may prove problematic, although the overall risk is small. Decision has
been made to keep heavy comments and code snippets if we were to revert
back somehow to the previous situation."

the wizard to sending failures email was broken as the field partner_id
which is required was not present in the view and was thus ignored by
to web client when calling 'create'.

closes odoo/odoo#58461

Task: 2341593
Closes: https://github.com/odoo/odoo/pull/58299
X-original-commit: f2431535a84cf4475899c285d968618bdecca1fc
Signed-off-by: Sébastien Theys (seb) <seb@odoo.com>

addons/mail/wizard/mail_resend_message_views.xml

@@ -17,6 +17,7 @@
                             <field name="name" readonly="1"/>
                             <field name="email" attrs="{'readonly': [('parent.partner_readonly', '=', True)]}"/>
                             <field name="message" readonly="1"/>
+                            <field name="partner_id" invisible="1"/>
                             <field name="resend" widget="boolean_toggle"/>
                         </tree>
                     </field>