Add pagination for the Graphql client

[ericboucher]

The basic implementation done in #78 does not allow for pagination. If we are to use the graphql endpoint to get more data, we will need to implement pagination in the client.

[ericboucher]

https://stackoverflow.com/questions/48116781/github-api-v4-how-can-i-traverse-with-pagination-graphql

[ericboucher]

The pagination should be implemented in a way that allows for "deep pagination". I.e. look for the deepest next page token and rotate it until hasNextPage = false