Changes to List websites

added the new optional query request parameter website_types

the response property data/items/domain became nullable for the status 200

the response property data/items/root_directory became nullable for the status 200

the response property data/items/username became nullable for the status 200

the response property data/items/vhost_type became nullable for the status 200

added the optional property data/items/horizons_uuid to the response with the 200 status

added the optional property data/items/website_type to the response with the 200 status