Save blockchain data to elasticsearch database

[oxarbitrage]

We want to export block data (the whole block history) into an elasticsearch database so we can use kibana for data exploration.

TODO

• Use Rust elasticsearch crate in order to save blocks into elasticsearch.
  • Use a bulk request when wee are far away from the tip.
  • Reduce the bulk size when we get closer to the tip so we can have real time data in kibana as the chain is in sync.
• Hide all elasticsearch code behind a rust feature.
• Add a config section for elastic host, username and password.
• Manual test the full thing in Testnet.
• Create an entry in the book on how to setup and run.