Add pre-built network and story directory configs to geth

[linear]

To reduce risk of configuration sync, as well as to ensure better dev UX practices for our users, we should hardcode network genesis and configurations for our partner and public testnet, similar to how geth already has this for networks like Goerli.

On top of this, to prevent collisions for validators who run normal Ethereum nodes, and to provide better sane default data folders for different users, we should update the default folder under our own directory recommendation. As a proposal, we suggest the following:

OS X:

~/Library/Story/geth

Linux:

~/.story/geth