[FIX] account_peppol: add a warning for Belgium

Users need a helpful message for selecting the right EAS and Endpoint numbers.
In Belgium it should always be 0208 according to BOSA,
so we can display a warning message advising them to select that code for Belgian partners.

Part-of: odoo/odoo#142688

addons/account_peppol/i18n/account_peppol.pot

@@ -687,6 +687,14 @@ msgid ""
 "to Live."
 msgstr ""
 
+#. module: account_peppol
+#: model_terms:ir.ui.view,arch_db:account_peppol.res_config_settings_view_form
+#: model_terms:ir.ui.view,arch_db:account_peppol.res_partner_form_account_peppol
+msgid ""
+"The recommended EAS code for Belgium is 0208. The Endpoint should be the "
+"Company Registry number."
+msgstr ""
+
 #. module: account_peppol
 #: model_terms:ir.ui.view,arch_db:account_peppol.res_config_settings_view_form
 msgid "The rejection reason has been sent to you via email."

addons/account_peppol/views/res_config_settings_views.xml

@@ -25,6 +25,12 @@
                                      invisible="not account_peppol_endpoint_warning">
                                     <field name="account_peppol_endpoint_warning"/>
                                 </div>
+                                <div class="alert alert-warning mt-3"
+                                     colspan="2"
+                                     role="alert"
+                                     invisible="country_code != 'BE' or account_peppol_eas in (False, '0208')">
+                                    The recommended EAS code for Belgium is 0208. The Endpoint should be the Company Registry number.
+                                </div>
                                 <div class="pt-3">
                                     <div class="row">
                                         <label string="Peppol EAS"

addons/account_peppol/views/res_partner_views.xml

@@ -7,6 +7,14 @@
             <field name="inherit_id" ref="base.view_partner_form"/>
             <field name="arch" type="xml">
             <data>
+                <xpath expr="//field[@name='ubl_cii_format']" position="before">
+                    <div class="alert alert-warning"
+                         colspan="2"
+                         role="alert"
+                         invisible="country_code != 'BE' or ubl_cii_format in (False, 'facturx') or peppol_eas in (False, '0208')">
+                         The recommended EAS code for Belgium is 0208. The Endpoint should be the Company Registry number.
+                    </div>
+                </xpath>
                 <xpath expr="//field[@name='peppol_endpoint']" position="after">
                     <field name="account_peppol_is_endpoint_valid" invisible="1"/>
                     <field name="account_peppol_validity_last_check" invisible="1"/>