[imp] account: add unique constraints on journal group names

Journal groups name are used as an identifier in reports,
namely on financial reports when a company has different reporting requirements
- on company level
- on consolidated level
- according to IFRS standards

This will add a constraints to ensure that groups name are unique.

Task id #2759252

closes odoo/odoo#85958

Signed-off-by: Laurent Smet <las@odoo.com>

addons/account/models/account_journal.py

@@ -28,6 +28,9 @@ class AccountJournalGroup(models.Model):
         check_company=True)
     sequence = fields.Integer(default=10)
 
+    _sql_constraints = [
+        ('uniq_name', 'unique(company_id, name)', 'A journal group name must be unique per company.'),
+    ]
 
 class AccountJournal(models.Model):
     _name = "account.journal"