Changes to List the vendor directory

the response's body type changed from array null to object for status 200

added the new optional query request parameter cursor

added the new optional query request parameter limit

added the non-success response with the status 409

added the non-success response with the status 422

added the non-success response with the status 500

added the non-success response with the status 503

added the optional property $schema to the response with the 200 status

added the optional property next_cursor to the response with the 200 status

added the required property revision to the response with the 200 status

added the required property vendors to the response with the 200 status

endpoint added