Handling BlockBatches in Geth at `SendBlockBatches` endpoint (eth_sendBlockBatches)
Other:
* Adding PR template
* Adding ability to set timestamp and making blocks use configured timestamp
* Adding ability to encode original tx nonce in calldata
* Adding L1MessageSender to Contract Creation Txs
The contributing instructions in the README are not in the GitHub contributing
guide, which means that people coming from the GitHub issues are less likely to
see them.
