erp5_oauth2_authorisation: get user by id instead of login

That way, we do not require creation of a login at all to use OAuth.

bt5/erp5_oauth2_authorisation/DocumentTemplateItem/portal_components/document.erp5.OAuth2AuthorisationServerConnector.py

@@ -1255,7 +1255,7 @@ class OAuth2AuthorisationServerConnector(XMLObject):
     """
     portal = self.getPortalObject()
     uf = portal.acl_users
-    user = uf.getUser(user_id)
+    user = uf.getUserById(user_id)
     if not hasattr(user, 'aq_base'):
       user = user.__of__(uf)