chore(kt-devnet): add config file to run against holesky L1

[samlaf]

The optimism-package feature to use an external_l1_network (from ethpandaops/optimism-package#104) is severely underdocumented, and also under-featured...

Doesn't work for our needed use case... seems like the feature was only implemented to target another locally deployed ethereum_package.

It doesn't work with holesky for a few reasons:

1. hardcoded addresses that are using the junk mnemonic (can prob be changed to all use the priv_key instead?)
2. op-deployer is always run. There's no way to turn it off and point to pre-deployed contracts. This means it would waste a lot of ETH everytime we run it. Plus right now op-deployer execution is timing out after 180 seconds. Prob takes more than 3 minutes to deploy against a real network...

I'm sure there are more reasons that we'll discover if we decide to change optimism-package to support this. Is this something we absolutely need at this time though? Are there any other workarounds we could use?

[bxue-l2]

@samlaf do you still want to merge it?