As a user of Synthetic Monitoring
I want to know the SpeedIndex of each page I test
So that I can get an indication of visual performance

ACs:

• Capture and store SpeedIndex for each step of a real browser (Synthetic) test
• SpeedIndex is available in the reporting UI (e.g. performance breakdown, exploratory view etc.)

Note there are different implementations for gathering SpeedIndex, such as from Lighthouse, visual progress (that requires filmstrip frames), and paint events.