Add marketing consent to signup form

### Description

GDPR and best practices support adding an explicit request for marketing consent from new signups. This issue is to add a checkbox to the signup page that:

1. Lets users check a (default 'no') box to consent to receiving marketing communications
2. Records that preference (Values: yes, no) to our database
3. Adds the user to the marketing email subscription type in HubSpot.

### Epic/Story

_No response_

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate