phongo_cursor_advance_and_check_for_error() should use mongoc_cursor_error_document() instead of mongoc_cursor_error(), as the former exposes data that can be used to populate the result document and/or error labels on an exception.

Currently, executeQuery() is limited to throwing a ServerException on server errors, which does not include the result document. With this change, phongo_cursor_advance_and_check_for_error can start using phongo_throw_exception_from_bson_error_t_and_reply() to throw a CommandException and make the result document accessible to the user.

While 1.5.x does not expose error labels on RuntimeExceptions (PHPC-1222), this change will also ensure that query errors expose error labels in 1.6.0, which will be helpful for applications utilizing transactions.