op-node,op-program: Ability to skip L1 chain config for L3s

[sebastianst]

We have recently introduced the necessity to provide op-node & op-program with the L1 chain config. For known L1s like Mainnet or Sepolia this can be skipped, as it is read automatically from the configs embedded into op-geth.

L3s now have to provide the chain configs of their L2 parent chains like OP/Base sepolia/mainnet. However, for L3s, we don't even strictly need the chain config of their parent chains, because it's currently only used inside derivation to calculate the blob base fee for the L1 attributes. But L2s have blobs disables, so this always results in the trivial value of 1.

To solve this, I suggest we add a flag like --l3 that changes some behavior and requirements on other flags, e.g. not requiring the L1 chain config to be provided. Then inside attributes derivation, we can safely just use 1 for the blob base fee if there's no chain config. We could furthermore auto-set the L3 flag if the L1ChainID is a known L2 chain ID.

Related configurability issue for L3s: #18009

[ajsutton]

Could we also detect if the "L1" chain ID is a known L2 chain ID and automatically apply the L3 behaviour similar to how we automatically recognise L1 mainnet and sepolia?

[sebastianst]

Could we also detect if the "L1" chain ID is a known L2 chain ID and automatically apply the L3 behaviour similar to how we automatically recognise L1 mainnet and sepolia?

Yes, we should definitely do that, so it just works™️ for most L3s.