Add notebooks from Contributoor datapoints

All our current notebooks are generated from Xatu Sentry data. Sentry nodes tend to be hyperconnected and may therefore see lower latency than the average Eth node. Xatu has another database holding Contributoor datapoints, backed by a different schema. See https://lab.ethpandaops.io/xatu/contributors.

We should aggregate and display these datapoints into a new category of notebooks.