CoilWM2Preview per Niq

This is a publishing for an experimental version of the extension currently published at
https://cup.aihedy.com/en-US/firefox/addon/coil/

We are currently implementing the new Web Monetization spec proposal @ https://webmonetization-preview.netlify.app/

The branch:
https://github.com/coilhq/web-monetization-projects/pull/2424

We need an easy way for people to test out this support without building from source each time there's an update.