Identify smoothed+raw paired signals in JSON for counts displays

[krivard]

Last week, we decided on using a 7-day average (smoothed) signal to determine the color of a region, while using the raw daily count in the tooltip and time series. The API serves both signals, but we need a way to tell the map which signal is which.

Adam and I came up with the following syntax, but @rhansolo if there's a better/nicer/easier way to do this let me know.

{
      name: 'Cases per capita',
      id: 'jhu-csse',
      tooltipText:      'Daily confirmed COVID-19 cases per 100,000 people, based on data reported by Johns Hopkins University',
      mapTitleText:  'Daily confirmed COVID-19 cases per 100,000 people',
      chartTitleText: 'Daily confirmed COVID-19 cases per 100,000 people',
      yAxis: 'Cases per 100,000 people',
      format: 'raw',

     signal: {raw:'confirmed_incidence_num', smoothed:'confirmed_incidence_7dav_num'},**

      levels: ['msa', 'county', 'state'],
official: true
    },

Long term we may be interested in pursuing something like cmu-delphi/delphi-epidata#131, but that's not something that can be done for 1.4 and I think we want to support the smoothed color + raw time series behavior for this release as part of the "color revisions" viz deliverable if we can.