Two new events are added:
- "inactive_tabs_expanded" for when the inactive tabs section is expanded
- "inactive_tabs_collapsed" for when the inactive tabs section is collapsed
For tracking when an inactive tab is opened / closed I've repurposed the
existing tabs tray telemetry (since the functionality uses the same code)
- tabs_tray.opened_existing_tab
- tabs_tray.closed_existing_tab
to support an extra "source" key indicating the feature from which a tab was
opened or closed. The current values for this new key are:
- "Tabs tray" for when a tab was opened/closed from tabs tray
- "Inactive tabs" for when a tab was openes/closed from the Inactive tabs
section of the tabs tray.