[FIX] account: field commercial_partner_id should be compute_related=True

OPW: 716163
This is needed to fix the following problem: adding a partner to res_partner.child_ids will mark all element of child_ids as 'todo'
and trigger a write on res_parner.commercial_partner_id for all element of the child_ids and then on the related field
account_invoice.commercial_partner_id. This can cause problem if partner in child_ids belong to different company and have invoices. This will throw a
read access error when doing the _write method of account_invoice. Adding the compute_related=True to account_invoice.commercial_partner_id
ensure that the _write on that field is done in sudo.

addons/account/models/account_invoice.py

@@ -313,7 +313,7 @@ class AccountInvoice(models.Model):
         default=lambda self: self.env.user)
     fiscal_position_id = fields.Many2one('account.fiscal.position', string='Fiscal Position', oldname='fiscal_position',
         readonly=True, states={'draft': [('readonly', False)]})
-    commercial_partner_id = fields.Many2one('res.partner', string='Commercial Entity',
+    commercial_partner_id = fields.Many2one('res.partner', string='Commercial Entity', compute_sudo=True,
         related='partner_id.commercial_partner_id', store=True, readonly=True,
         help="The commercial entity that will be used on Journal Entries for this invoice")