Checkmk Werk 13655: REST API host_config: fix the create and update endpoints when including a host attribute

ID: 13655 Title: REST API host_config: fix the create and update endpoints when including a host attribute Component: REST API Level: 1 Class: Bug fix Version: 2.2.0i1 In the previous version, the create and update host endpoints returned a 500 error when the user tried to register or modify a host with attributes. This werk fixes this behaviour and returns a 400 error when an invalid attribute is included.