Add graph database and IAM roles to it

[reiddhughes]

A graph database looks like a good choice for tracking and querying the relationships between cloud resources. This is especially true for IAM roles where chains of roles can assume each other.

It's possible to write an algorithm to traverse the network, but an in-memory graph database probably does it better and for less work. We should select a graph database to work with and try populating it with some fake IAM roles. We probably want to go with an in-memory version because this tool is meant to be run locally and we don't want to deal with hosting a database. Another benefit of using a graph db, especially one that uses open query languages, is that we might be able to allow the user to specify the query.

It might also be an option to look up any graph searching libraries that Go has.

[reiddhughes]

Some considerations:

• https://memgraph.com/
• http://redisgraph.io/
• https://sqlite.org/index.html (not a graph db, but one of the best in-memory DBs)