Add OptimismGenesis fields type

[mattsse]

Describe the feature

Optimism includes additional info in the genesis file.

we don't want to pollute the eth genesis bindings with these, instead we should bundle them in a separate type:

See for example:

https://raw.githubusercontent.com/paradigmxyz/alphanet/331aaea21649e1295d676b73a4ce206bbfbdfe04/crates/testing/resources/etc/genesis.json

This includes OP timestamps + optimism object

This type can be added to node-optimism crate for now

cc @fgimenez

Additional context

No response

[andrzejSulkowski]

I'd like to try this one

[andrzejSulkowski]

It's the first time I will be contributing to this repo and my second time in total so I just would like to clarify quickly...
Steps to tackle this issue are:

1. Identify differences between the genesis file of optimism and eth
2. Extract the differences into a separate type (inside node-optimism crate)

Thank you in advance!

[fgimenez]

hey @andrzejSulkowski this task is blocking other areas of work and it is already in progress, sorry for not updating its state.

pls take a look at other good first issues to work on! D-good-first-issue Nice and easy! A great choice to get started

[Jrachman]

temporary solution i put together that programmatically launches the dev node with custom genesis updates: https://github.com/otim-xyz/alphanet/blob/main/examples/custom-genesis-dev-node.rs