Fix code and codehash indexing

[i-norden]

Currently writing the tx_data for deployment txs as the codebytes, this is not producing the correct code hashes. There must be some processing step on the tx_data before it is stored as codebytes.

• Create http endpoint for statediffing geth to fetch all codehash => code pairs

• Modify the statediffing service to emit/write codehash => code pairs for any deployment txs at the payload's block height

• Script/command to fetch missing historical from the http endpoints

• Script/command to remove malformed entries (optional)

[i-norden]

We aren't going to worry about a script/process to repair missing code and codehashs, we are just resyncing completely: https://github.com/vulcanize/ops/issues/76