Graph Debugging Tool

[dsherret]

The graph is getting very complex for TypeScript. In the future, there needs to be a tool that quickly answers the following questions:

1. What path in the graph printed out the final text?
2. What paths did the printer consider before it got to the final text and what was the state of everything as it traversed the graph?

I'm thinking there are two tasks here:

1. Output snapshots of every step in the printer and its current state (along with the writer's state) along with another set of data that describes the generated IR. There should be IDs on each node in order to link up with the snapshot data.
2. Take that final data and show the graph in the browser. Then have a slider that allows someone to progress through the printer snapshots. As they progress, it should show the current state of everything along with showing the current node and the path the printer has taken.

This would be very cool and save me a lot of time. It would also be a good educational tool to explain how dprint works.