[ENHANCE] Nodes as networkx graph

[cooko-mcmaster]

Describe the user story this enhancement fulfills
As a researcher, I want to express my research processes in terms of a set of tasks and the relationship between them, so that I can compose meaningful and functional models of the behavior of my research.

Describe the expected behavior this enhancement performs
By using networkx we gain all of the benefits and functionality of a mature graph data structure as well as compatibility with other programs.

Describe the testable outcome this enhancement produces
All existing pipelines work with this new implementation