feat: create generalized networkx constructor

[jsstevenson]

• house network/graph related functions in their own modules. This effectively duplicates some stuff that we've done previously for the dash app, but I think we can move/collapse that at a later date (i.e. I'm not making any breaking changes here yet, just adding in redundant functionality for now)

The motivation is to support generalization of some of the graph visualization tooling -- so that we aren't as tied to just interactions and can more easily support other kinds of queries (or combos of queries???)

[mcannon068nw]

@rbasu101