Milestone 2 - Filecoin chain and state extractors

[i-norden]

• Implement individual chain and state extractors for Filecoin data.
  • Based on fil-fip36-vote-tally parse state code.
  • ADT node/actor model extractor.
  • Chain model extractors.
  • Define and expose generic block stream interface.
  • Supports two modes - realtime and historical - that can be configured with the appropriate data source (streaming data from a live node or reading data from an offline database)
• Implement snapshotting service.
  • Uses a state extractor that processes the entire state at a given height, not just the differential set between two states.
  • This state extractor is essentially the fil-fip36-vote-tally parse state code that has been modified to process internal nodes. Also analogous to our ipld-eth-state-snapshot tool.
• Unit and integration testing.
• Basic documentation.