Unblock EVM RPC emulation

[SebastienGllmt]

• add tx hash to the database (see add txHash to the submittedData passed to the stf #392 which calculates them, but doesn't store them. See scheduled_data_tx_hash)
• create a block header standard and a block hash based off of it. Notably, we need to make sure it has the following properties:
  • it includes a timestamp (see add BlockHeader type with timestamp info to the stf call #402 which adds it in-memory, but we need it from the database)
  • it includes a pointer to the previous block hash
• ensure that a timestamp field is present in block headers
• fetch logs for a transaction (see add event logs to stf and db #409)
• a way to fetch the transaction nonce (low priority I think)
• A definition of "tx index" in a block. The natural definition for this is to sort by the database ID for values that have the same block, but this is tricky because there are 2 tables (historical_game_inputs and scheduled_data). The order of these IDs is also funnel-dependent which makes breaking changes frequent because of the way funnel fetch ordering works, but I don't think we can get around that. Right now we process the scheduled data in the STF before the historical data, so we can keep the same order
• Right now we delete scheduled data after it gets processed, but this breaks these historical queries