Firebase Cloud Functions for the demo application.
This function adds a new document to the mail collection on new user creation - this collection is listened to by the Firestore Send Email extension
and sends a welcome email to the new user.
This function triggers on new order create and sends an initial order update SMS to the user (if they've setup a phone number on their account) via the Twilio Send Message extension by writing to the messages collection on Cloud Firestore.
This scheduled function deletes all user data every 24 hours - useful only for the purpose of this demo.