Support for fetching non-esri JSON

The doc says you can point at JSON files, but do these static files still need to conform to a feature service like response?

Per: https://esri.github.io/cedar/examples/inlined-data.html It states the expected input needs to look like...
```
{
...other properties...
features:[
{
"attributes": {
"ZIP_CODE": 20005,
"TOTAL_STUD_SUM": 327
}
```
I was hoping to point a chart at an API, like https://city-of-ottawa-dev.apigee.net/open311/v2/requests.json inside the ArcGIS Hub. Everything inside this particular JSON request starts immediately as items inside a list. No `features`, no `attributes` keys.

Start by reviewing the inlined-data example at esri.github.io/cedar/examples/inlined-data.html and compare its features/attributes shape with the Open311 requests.json response. Determine where Cedar fetches and interprets chart data; done means a chart can consume list-based JSON without features or attributes keys, with the supported input documented.

Written by the indexing model from the issue text.