Investigate r5py for generating static analysis

Following evaluation in #600, we discovered Taui is fetching and deriving network data from static analysis output generated by Conveyal and hosted on their S3 buckets. This is currently blocked until we understand how ECHO wants to proceed and learn more about the state of analysis. Should we take over generated analyses, we should begin with investigating the local setup of `r5py` as a simple interface for an r5 engine, what we would use for building a network graph and then running analysis.

Start by reviewing issue #600 and the current assumptions about Conveyal-generated analyses and S3-hosted network data. Investigate the local setup of r5py as an interface to an R5 engine, including whether it can build a network graph and run the needed analysis. Done means documenting the findings and a recommendation for how ECHO should proceed.

Written by the indexing model from the issue text.