[template request] MMS ticketing example

It would be nice to have an example template that shows how an MMS powered ticketing could work.

User flow:

• Person visits a website (fictitious "Happy Hour" event website)
• Person enters phone number and name
• Person clicks "Issue ticket"
• Button click will trigger a Twilio Function
• Twilio Function will generate a QR code (this can contain a basic JSON for example with the name)
• QR code is sent together with a message of Hi ${name}! Thanks for registering for the happy hour event. Here's your ticket! via Twilio Messaging (SMS with mediaUrl property)

Files needed

• index.html, main.js and styles.css in an assets/ directory for the event website
• issue-ticket.js in functions/ to send out the MMS
• generate-qr-code.js as functions/ that receives data in a request parameter to generate a QR code and return it as an image data. (to be used mediaUrl prop of the MMS)

Start with the requested assets/index.html, assets/main.js, assets/styles.css, functions/issue-ticket.js, and functions/generate-qr-code.js, then trace how the website request reaches the Twilio Function. The work is done when a name and phone number produce a QR-code image and an MMS containing the specified greeting and media URL.