Track chart datapoints from their sources and provide a tabular view of chart data
Summary: Depends on D20815. Ref T13279. Give datapoints "refs", which allow us to figure out where particular datapoints came from even after the point is transformed by functions. For now, show the raw points in a table below the chart.
Test Plan: Viewed chart data, saw reasonable-looking numbers.
Maniphest Tasks: T13279
Differential Revision: https://secure.phabricator.com/D20816