FxA Multiple Devices metrics about fxa HOT 2 CLOSED

/cc @philbooth. After a product/project discussion last week, we decided it's more important to work on this from a metrics standpoint first rather than from a "session status dashboard" perspective. The set of enabling work is broadly similar though:

• Add last access time to login sessions (mozilla/fxa-auth-server#983)
• Add user agent information to login sessions (mozilla/fxa-auth-server#983)
• Add optional client-provided device ID to login sessions (mozilla/fxa-auth-server#988)
• Add scripting to extract the core multi-device metrics from the db and dump them into our metrics pipeline (mozilla/fxa-auth-db-mysql#72)
• Add multi-device graphs to the metrics dashboard
• Have Desktop Firefox pass the sync client GUID as its device ID when logging into Sync
• Have Fennec pass the sync client GUID as its device ID when logging into Sync
• Have Firefox for iOS pass the sync client GUID as its device ID when logging into Sync

from fxa.

Exporting these FEATURE cards from Aha has not turned out to be useful in practise, I'm closing them in favour of more direct use of Aha.

This feature lives at: https://mozilla.aha.io/features/FXA-21

from fxa.