Define a genesis config file

[jbearer]

This aims to separate onchain data, which must be the same for all nodes (chain ID, base fee, etc) from node-specific configuration. Node configuration continues to be done via environment variables, whereas onchain data is defined in a configuration file which we can distribute to all node operators when launching a network. This should greatly simplify coordination and reduce the frequency of errors due to misconfigured nodes.

[jbearer]

Changed base to #1390, since this was touching a lot of the same code. We'll have to merge this later anyways, since it requires a substantial reworking of the deploy config.