[FIX] l10n_fr_pos_cert: fpos settings

The computation of hash integrity depends on the field
`tax_ids_after_fiscal_position`. However, this field is computed, but
not stored.

It means that if one modifies a fiscal position used in the POS, the
computation of `tax_ids_after_fiscal_position` will change.
Consequently, the hash computation of the order will be modified, and
the hash integrity of the journal will be corrupted.

We prevent the modification of the taxes implied in a fiscal position if
any POS order use it.

Closes #32665
opw-1969009

closes odoo/odoo#32701

Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>

addons/l10n_fr_pos_cert/i18n/l10n_fr_pos_cert.pot

@@ -66,6 +66,11 @@ msgstr ""
 msgid "Corrupted data on point of sale order with id %s."
 msgstr ""
 
+#. module: l10n_fr_pos_cert
+#: model:ir.model,name:l10n_fr_pos_cert.model_account_fiscal_position
+msgid "Fiscal Position"
+msgstr ""
+
 #. module: l10n_fr_pos_cert
 #: model:ir.ui.menu,name:l10n_fr_pos_cert.pos_fr_statements_menu
 msgid "French Statements"
@@ -137,7 +142,13 @@ msgid "This session has been opened another day. To comply with the French law,
 msgstr ""
 
 #. module: l10n_fr_pos_cert
-#: code:addons/l10n_fr_pos_cert/models/account_bank_statement.py:11
+#: code:addons/l10n_fr_pos_cert/models/account_fiscal_position.py:14
+#, python-format
+msgid "You cannot modify a fiscal position used in a POS order. You should archive it and create a new one."
+msgstr ""
+
+#. module: l10n_fr_pos_cert
+#: code:addons/l10n_fr_pos_cert/models/account_bank_statement.py:12
 #, python-format
 msgid "You cannot modify anything on a bank statement (name: %s) that was created by point of sale operations."
 msgstr ""

addons/l10n_fr_pos_cert/models/__init__.py

 import account_bank_statement
+from . import account_fiscal_position
 import res_company
-import pos
\ No newline at end of file
+import pos

addons/l10n_fr_pos_cert/models/account_fiscal_position.py

+# -*- coding: utf-8 -*-
+
+from odoo import _, models
+from odoo.exceptions import UserError
+
+
+class AccountFiscalPosition(models.Model):
+    _inherit = "account.fiscal.position"
+
+    def write(self, vals):
+        if "tax_ids" in vals:
+            if self.env["pos.order"].sudo().search_count([("fiscal_position_id", "in", self.ids)]):
+                raise UserError(
+                    _(
+                        "You cannot modify a fiscal position used in a POS order. "
+                        + "You should archive it and create a new one."
+                    )
+                )
+        return super(AccountFiscalPosition, self).write(vals)