Add application notifications tray #8964
Description
We should be using fewer toasts in general, and we need other ways to communicate long-running processes and successes for those processes, in a dedicated space that isn't overlapping the primary interface like toasts do. The most egregious example of this is our export "loading" style toast, but there are certainly more.
We should instead design an application notifications tray that presents UI when new notifications are added. Here are some things we should decide about it:
- Where is the tray? In the app header, or perhaps the bottom status bar somewhere?
- Are notifications persisted across openings of the tray, are they persisted across runs of the app?
- Do notifications have "read" and "unread" statuses?
- Do toasts (any that remain after this and Remove unnecessary toasts #8961) relate to notifications? Do they appear near the tray?