Improve Activity event handling in the UI
- fixes#252 found that the Activity page showed activity inconsistent
with /api/metrics
- Change data structure for event metrics to array.
- Add Event stream connections status indicator
Major internal refactor to use an event bus to pass event/messages along. These changes are largely invisible user facing but sets up internal design for real time stats and information.
- `--watch-config` logic refactored for events
- remove multiple SSE api endpoints, replaced with /api/events
- keep all functionality essentially the same
- UI/backend sync is in near real time now
