Add an onboarding page for opt-in consent
Mozilla's new privacy policy requires an opt-in consent to the collection of personal information. Since IP addresses are personal info, we need to have users consent before enabling their snowflake proxy.
Notes:
- the link to the privacy policy right now is dead. We can update it when #34 (closed) is ready.
- this is a bit messy, I'm not even sure that the event dispatcher message passing in consent.js is necessary or the right way to do things, but it's at least functional