[User Story] User should get a notification when a new study is available

[knowtheory]

Story

As an existing Rally user, I want to be notified when new studies are available so that i don't miss out on new studies, and can decide whether to join new studies.

Definition of Done

Rally can send some kind of notification to users (badging, or actual notifications or something)

Tasks

• identify the easiest notification mechanism
• implement notification mechanism

[rhelmer]

I think one consideration we want to keep in mind: filter notifications based on the whether the user is already enrolled in a particular study, or has already dismissed an alert.

The naive way to do this would be to e.g. highlight the badge, send a browser notification, etc. each time remote-settings is changed, or each time a new study is published, etc. However I think we want the control to be a little more fine-grained, for instance we might to only show notifications when:

1. a new study is published
2. the study is unpaused
3. the user has not already dismissed notifications related to this study

If a study becomes paused, we should stop showing notifications until it becomes unpaused, as there is no action to take.

We should also decide exactly what sort of notifications we want to send, I'd suggest:

• a single browser notification per study, subject to the conditions above
• a persistent badge notification (I'm not sure a number makes sense, maybe just a "NEW" badge or similar?)

[marniepw]

See also: https://bugzilla.mozilla.org/show_bug.cgi?id=1674916