Make studies contingent on user consent

[jonathanmayer]

One way to handle this would be support for listeners in the Consent module. For example, a study module could register a listener for consent state changes, and then start data collection if the user consents or stop data collection and delete data if the user withdraws consent.

[jonathanmayer]

In future we might also want to send a Telemetry event noting that the user has withdrawn consent, so we can delete their data on the backend.

[akohlbre]

closed in 64e4b9e No telemetry ping to delete remote data yet (will add with rest of telemetry work)