cookie needed to link form submissions

I added modifications to public function submitHubspotForm in branch 3359121-cookie-needed-to as described here:

https://community.hubspot.com/t5/APIs-Integrations/Hubspot-API-forms-The...

The bug has been resolved since this patch was created.

The proposed solution also creates a problem, because if the cookie is sent back to HubSpot empty, we receive a message in return. Please see below.

HTTP error when submitting HubSpot data from Webform "XXXX":

{"status":"error","message":"The request is not valid","correlationId":"xxxxxxx","errors":[{"message":"Error in 'context.hutk'. '' is not a valid Hutk","errorType":"INVALID_HUTK"}]}