Store fides_consent cookie on the root domain of the Privacy Center

[NevilleS]

Closes #2070

Code Changes

• Calculate the root domain (based on window.location)
• Save the cookie using the root domain

Steps to Confirm

• Ran nox -s test_env and confirmed cookie still writes out unchanged
• Deploy privacy center to a subdomain and test

Pre-Merge Checklist

• All CI Pipelines Succeeded
• Documentation:
  • documentation complete, PR opened in fidesdocs
  • documentation issue created in fidesdocs
• Issue Requirements are Met
• Relevant Follow-Up Issues Created: Add support to fides_consent cookie for root domains with second-level domains (co.uk, co.jp, etc.) #2072
• Update CHANGELOG.md

Description Of Changes

This has one major issue, which is that it'll only work for "normal" TLDs like ".com", ".co", etc., but will calculate the root domain incorrectly for sites that use second-level domains like "example.co.uk" or "example.co.jp", etc.