Set up dynamic content publishing data flow

[devnook]

• [ ] Investigate Firebase functions / Cloud functions webhook option
• [ ] Set up webhook to sanity to post into
• [ ] Secure the webhook with api secret
• [ ] generate an .md template out of PortableText (basic content only, no serializers)
• [ ] Make sure 11ty is fast enough to not timeout on webhook invocation #3708
• [ ] Add call to Github to store canonical/backup data
• [ ] Add call to Some Storage Service (TM) to store dynamic file for quick publishing
• [ ] Resolve scheduling conflicts between dynamic content and staticly build files
• [ ] Come up with a solution for conflict resolution between Sanity and Github
• [ ] Add security checks to not leak unpublished data / files accidentally