As a User I want to understand sync failures

[st3fan]

Sync can fail for many reasons. There could be a temporary server (reachability) problem, or your account could be closed, or your password changed, etc. On Firefox for iOS we did not have a good way to report these failures, which resulted in lots of user confusion.

Maybe we can learn something from how Desktop handles this?

• Integrate feature-sync component #206 feature-sync integration
• Report Sync/FxA errors mozilla/application-services#399 library support for knowing what went wrong
• Add UI for indicating sync/FxA failures #208 UI for displaying failures
• Ability to display notifications and handle notification interactions - a notification helper android-components#1374 (optional) UI for display failures as notifications