pc/consent: Restructure consent src dir to make modle/browser distinction clearer

[ssangervasi]

Start of #1801

Code Changes

• Move src/index.ts to src/fides-consent.ts to make it clearer it becomes dist/fides-consent.js
• Move src/cookie.ts to src/lib/cookie.ts
• Add src/lib/index.ts and use it as the root of the module build, so that if we want to add other code that isn't specifically for cookies (like a Shopify helper) we can have multiple files.

Steps to Confirm

• Nothing should change 🙂

Pre-Merge Checklist

• All CI Pipelines Succeeded
• Documentation Updated:
  • documentation complete, or draft/outline provided (tag docs-team to complete/review on this branch)
  • documentation issue created (tag docs-team to complete issue separately)
• Issue Requirements are Met
• Relevant Follow-Up Issues Created
• Update CHANGELOG.md