[Offline sync] Consolidate and simplify notifications

[gino-m]

We should have notifications for these background operations:

• [ ] New LOIs added to a job by organizer
• [ ] New jobs added to a survey by organizer
• [ ] Submitted data uploaded (notify about photos separately?)

Offline basemap tiles download can happen in the background but the status should be reported in the UI rather than notification.

The notifications are currently transient, but with #1125 they should be persistent.