Get the app's data sources

Each source that sends the app's data (client SDK per platform, server SDK per language, connected provider, billing, history import) with its events in the last hour and 24 hours, SDK and app versions, and state (sending, quiet, never, error, done), plus what became of the last 24 hours of events. The event health monitor rolls sources up every hour; rollup_ready is false until it has, and the 24-hour figures are then null.