Tree builder

[zkat]

Need to create a standalone tree builder library that can represent and manipulate dependency trees. It needs to be able to read lockfiles, read node_modules, and have an understanding of links, abstract nodes, and physical nodes.

Notes

• petgraph might be helpful here. Especially StableGraph.

Blocked

I'd like to have a working HTTP client for this so we can build out a sample graph based on actual data (#17)