[REF] various: apply main attachment mixin on models that use the feature

Add mail.thread.main.attachment in the inheritance chain of all models that
use the main attachment feature.

Note that we remove the main attachment from crm_case_15 of the demo data as
crm_lead doesn't use that feature.

Task-2648976

Part-of: odoo/odoo#110734

addons/account/models/account_move.py

@@ -49,7 +49,7 @@ EMPTY = object()
 
 class AccountMove(models.Model):
     _name = "account.move"
-    _inherit = ['portal.mixin', 'mail.thread', 'mail.activity.mixin', 'sequence.mixin']
+    _inherit = ['portal.mixin', 'mail.thread.main.attachment', 'mail.activity.mixin', 'sequence.mixin']
     _description = "Journal Entry"
     _order = 'date desc, name desc, id desc'
     _mail_post_access = 'read'

addons/account/models/account_payment.py

@@ -7,7 +7,7 @@ from odoo.tools.misc import format_date, formatLang
 class AccountPayment(models.Model):
     _name = "account.payment"
     _inherits = {'account.move': 'move_id'}
-    _inherit = ['mail.thread', 'mail.activity.mixin']
+    _inherit = ['mail.thread.main.attachment', 'mail.activity.mixin']
     _description = "Payments"
     _order = "date desc, name desc"
     _check_company_auto = True

addons/crm/data/crm_lead_demo.xml

@@ -444,10 +444,6 @@ Andrew</p>]]></field>
             <field name="subtype_id" ref="mail.mt_comment"/>
             <field name="attachment_ids" eval="[(6, 0, [ref('msg_case15_attach1')])]"/>
         </record>
-        <!--Main attachment is usually registered by message_post, so here we must set it manually-->
-        <record id="crm_case_15" model="crm.lead">
-            <field name="message_main_attachment_id" ref="msg_case15_attach1"/>
-        </record>
         <record id="msg_case15_3" model="mail.message">
             <field name="subject">Re: Plan to buy RedHat servers</field>
             <field name="model">crm.lead</field>

addons/hr/models/hr_employee.py

@@ -26,7 +26,7 @@ class HrEmployeePrivate(models.Model):
     _name = "hr.employee"
     _description = "Employee"
     _order = 'name'
-    _inherit = ['hr.employee.base', 'mail.thread', 'mail.activity.mixin', 'resource.mixin', 'avatar.mixin']
+    _inherit = ['hr.employee.base', 'mail.thread.main.attachment', 'mail.activity.mixin', 'resource.mixin', 'avatar.mixin']
     _mail_post_access = 'read'
 
     # resource and user

addons/hr_expense/models/hr_expense.py

@@ -15,7 +15,7 @@ from odoo.tools import email_split, float_repr, float_compare, is_html_empty
 class HrExpense(models.Model):
 
     _name = "hr.expense"
-    _inherit = ['mail.thread', 'mail.activity.mixin', 'analytic.mixin']
+    _inherit = ['mail.thread.main.attachment', 'mail.activity.mixin', 'analytic.mixin']
     _description = "Expense"
     _order = "date desc, id desc"
     _check_company_auto = True
@@ -784,7 +784,7 @@ class HrExpenseSheet(models.Model):
         =================================================================================
     """
     _name = "hr.expense.sheet"
-    _inherit = ['mail.thread', 'mail.activity.mixin']
+    _inherit = ['mail.thread.main.attachment', 'mail.activity.mixin']
     _description = "Expense Report"
     _order = "accounting_date desc, id desc"
     _check_company_auto = True

addons/hr_holidays/models/hr_leave.py

@@ -72,7 +72,7 @@ class HolidaysRequest(models.Model):
     _name = "hr.leave"
     _description = "Time Off"
     _order = "date_from desc"
-    _inherit = ['mail.thread', 'mail.activity.mixin']
+    _inherit = ['mail.thread.main.attachment', 'mail.activity.mixin']
     _mail_post_access = 'read'
 
     @api.model

addons/hr_recruitment/models/hr_applicant.py

@@ -22,7 +22,7 @@ class Applicant(models.Model):
     _name = "hr.applicant"
     _description = "Applicant"
     _order = "priority desc, id desc"
-    _inherit = ['mail.thread.cc', 'mail.activity.mixin', 'utm.mixin']
+    _inherit = ['mail.thread.cc', 'mail.thread.main.attachment', 'mail.activity.mixin', 'utm.mixin']
     _mailing_enabled = True
     _primary_email = 'email_from'