[FIX] mail: allow non-internal users to create chat from token

Follow up of odoo#90415
After removing the public field, the equivalent access is to set the
allowed group to empty.

closes odoo#114675

Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>

addons/mail/controllers/discuss.py

@@ -56,6 +56,7 @@ def _response_discuss_channel_from_token(self, create_token, channel_name=None,
                 channel_sudo = channel_sudo.create({
                     'channel_type': 'channel',
                     'default_display_mode': default_display_mode,
+                    'group_public_id': None,
                     'name': channel_name or create_token,
                     'uuid': create_token,
                 })

addons/mail/tests/test_mail_channel_as_guest.py

@@ -77,3 +77,9 @@ def test_mail_channel_public_page_as_portal(self):
 
     def test_mail_group_public_page_as_portal(self):
         self._open_group_page_as_user('portal')
+
+    def test_chat_from_token_as_guest(self):
+        self.env['ir.config_parameter'].set_param('mail.chat_from_token', True)
+        self.url_open('/chat/xyz')
+        channel = self.env['mail.channel'].search([('uuid', '=', 'xyz')])
+        self.assertEqual(len(channel), 1)