* op-chain-ops: ether migration

Updates the migration script to also migrate
eth balances from their legacy erc20 format.
It will find the balances given the input generated
from `l2geth` and the JS package responsible for parsing
that input and then migrate the balance and delete
the balance in the erc20 contract.

It also adds some additional sanity checks to ensure
that the data is completely accounted for so that
the script cannot be ran with insufficient or malicious
inputs.

fixup

* op-chain-ops: fix linting

lint

* op-chain-ops: update go.mod

* op-chain-ops: cleanup code

* op-chain-ops: fix go mods

* op-chain-ops: pass through chain id

* op-chain-ops: properly encode nonce
Co-authored-by: Matthew Slipper <me@matthewslipper.com>