TPR on Directed Graphs #175

Is your feature request related to a problem? Please describe.
TPR currently does not work on Directed Graphs, but there are papers that details how that can be done.
https://cdlib.readthedocs.io/en/latest/reference/classes/node_clustering.html#cdlib.NodeClustering.triangle_participation_ratio

In the paper referenced below, there are two major forms:

• A=>B, B=>C and A=>C (conduit-likes)
• A=>B, B=>C and C=>A (cycle)

Out of these two forms, multiple TPR can be derived, either by bidirectional connections, or triangular closure.

Reference.

• https://old-www.sandia.gov/~tgkolda/pubs/pubfiles/KlGlKo14.pdf
• https://www.cs.cornell.edu/~arb/papers/directed-closure-NWS-2020.pdf

Describe the solution you'd like
A clear and concise description of what you want to happen.

Describe alternatives you've considered
Converting the graph into an undirected graph for simplicities sake?