[reports] Audit and Unify dataFormat behavior for Vizes

[jhmullen]

Between Viz.jsx, Options.jsx, and a handful of custom vizes for the CMS (Table.jsx), there is a janky dataFormat problem that I would love for @greenrhyno to sort out and unify.

The origin of the situation was, among other complexities, @palamago's implementation of datawheel cart. Further, vizes are meant to be able to handle a number of situations for the data key:

• A straight up array of actual data, directly provided.
• A single string, pointing to a url, to use its payload.
• An array OF string urls, which are Promise.all'd and returned.
• I think, some combination of direct data AND urls (?)

This is implemented in several locations, between d3 dataLoad, dataFormat, and searching for the word hasMultiples.

Sorting this out has been a quagmire for me, and I would love for this to be smoothed out, readable, and unified.

I'd like to backport any changes to canon-cms as well (see #1214)