Build insight UI

[gregsexton]

This renders a debug trace given a static JSON file that is generated
by SKStore.

[gregsexton]

Carved out a PR for just the rendering while I continue working on the backend.

'Insight' is what I've been calling the debugger. It's more of a trace than a 'debugger', but in my experimentation this is much more useful - and it will work across machines, platforms, languages, etc.

I'll attach some screenshots.

[gregsexton]

Here I ask for a trace of a key produced by a left outer join.

You can zoom, pan around, adjust the positions of nodes, etc.

As you hover over files, the upstream dependencies - including reads performed by the mapper - are highlighted.

You can click in to the detail of how any file was produced. These are the collapsed sections.

Here we see the logic for the computation, with the full transitive closure. Using this we can understand exactly how the logic operated and why it produced this value.

Here are the out of band reads made compared to the input files the DAG fed the mapping function.