WIP: Implement related relationship access

[nohponex]

JSON API controller should be fixed at

/var/www/vivanteHealth/ostomate-api/vendor/phramework/jsonapi/src/Controller/Relationships.php:195

        //Gather ids form relationship
        foreach ($data as $resource) {
            $ids[] = $resource->id;
        }

because callback did not returned resources but string[]