Add telemetry events for relevant actions in app

[sandysage]

As the product owner, I want to know how users engage with the app to help inform decisions for future effort, while making sure users have control over whether or not their usage data is submitted.

Acceptance criteria

• All events should send Telemetry event data defined by the Mozilla product, data science, and legal teams
• The user should be able to disable usage data collection (Telemetry) via a setting

Engineering email thread about testing Telemetry: https://groups.google.com/a/mozilla.com/d/msgid/mobile-all/CABupmeDgMfjz%3Dqi4m%2B23BP2jL5%2ByQV-eruCcPRUMErQLyUZRZw%40mail.gmail.com?utm_medium=email&utm_source=footer

Requires #15