[IMP] microsoft_outlook: allow customizing the outlook endpoint

Purpose
=======
If we want to deploy Outlook for a custom organization, it might be
useful to be able to customize the endpoint used in the API request.

For that purpose, we added a system parameter to overwrite the default
endpoint.

Task-2811567

Part-of: odoo/odoo#88215

addons/microsoft_outlook/models/microsoft_outlook_mixin.py

@@ -47,13 +47,14 @@ class MicrosoftOutlookMixin(models.AbstractModel):
         Config = self.env['ir.config_parameter'].sudo()
         base_url = self.get_base_url()
         microsoft_outlook_client_id = Config.get_param('microsoft_outlook_client_id')
+        OUTLOOK_ENDPOINT = Config.get_param('microsoft.outlook.endpoint', self._OUTLOOK_ENDPOINT)
 
         for record in self:
             if not record.id or not record.use_microsoft_outlook_service or not record.is_microsoft_outlook_configured:
                 record.microsoft_outlook_uri = False
                 continue
 
-            record.microsoft_outlook_uri = url_join(self._OUTLOOK_ENDPOINT, 'authorize?%s' % url_encode({
+            record.microsoft_outlook_uri = url_join(OUTLOOK_ENDPOINT, 'authorize?%s' % url_encode({
                 'client_id': microsoft_outlook_client_id,
                 'response_type': 'code',
                 'redirect_uri': url_join(base_url, '/microsoft_outlook/confirm'),
@@ -124,9 +125,10 @@ class MicrosoftOutlookMixin(models.AbstractModel):
         base_url = self.get_base_url()
         microsoft_outlook_client_id = Config.get_param('microsoft_outlook_client_id')
         microsoft_outlook_client_secret = Config.get_param('microsoft_outlook_client_secret')
+        OUTLOOK_ENDPOINT = Config.get_param('microsoft.outlook.endpoint', self._OUTLOOK_ENDPOINT)
 
         response = requests.post(
-            url_join(self._OUTLOOK_ENDPOINT, 'token'),
+            url_join(OUTLOOK_ENDPOINT, 'token'),
             data={
                 'client_id': microsoft_outlook_client_id,
                 'client_secret': microsoft_outlook_client_secret,