telemetry: send an event when the state change

[guillaumerose]

On status change, the tray should send an event in the telemetry.
It will enable us to better understand what is happening and why the user is clicking on the button.

Also, maybe add the current status of the tray as a property in all events (click start, etc.).

We would see in Segment something like:
click start (current status = stopped)
status changed to starting
status changed to running
click stop (current status = running)
click delete (current status = stopping)
status changed to stopped