Send temp basal of 0 to NS while pump is suspended

[inventor96]

Is your feature request related to a problem? Please describe.
It appears that all IOB-related calculations handle pump suspends correctly (based on #879 and #922), but it would be nice to see a 0-basal represented in Nightscout.

Describe the solution you'd like
When a pump suspend occurs, a temp basal of 0 should be rendered on the graph in Nightscout. When a resume event occurs, the basal should be returned to the default for the given time, or whatever the calculated rate is at that time. This functionality could piggyback off of the work done in the PRs linked above.

Describe alternatives you've considered
An IFTTT applet could be created to respond to pump suspend and resume events, but the delay on the platform has been getting worse (at least for me), so that wouldn't be optimal. I think that any temp basal recalculation mid-suspend would throw off the graph, anyway?

Additional context
Ideas and considerations on implementation are definitely welcome! I could see this being tricky with the possibility of temp basal recalculations mid-suspend. Nightscout might need some changes to allow a temp basal with an indefinite duration, too.

Would it be better to create "Pump Suspend" and "Pump Resume" treatment events to Nightscout, change OpenAPS to use those instead of notes, and then change the basal rendering to include those events?