feat(`anvil`): fully offline mode for `anvil` fork

[exp0nge]

Component

Anvil

Describe the feature you would like

It does not seem like it's currently possible to do a fully offline version of an anvil fork. Even with the following startup commands, it still tries to reach out to the RPC:

anvil --fork-url https://sepolia.base.org --optimism --fork-block-number 20702367 --fork-chain-id 84532 --host 0.0.0.0 --load-state ~/state.json --no-mining

(I ensured that both state.json and storage.json exist for that fork number).

when attempting to call eth_chainId

I get

Error: failed to get fork block

Caused by:
   0: error sending request for url (https://sepolia.base.org/)
   1: error sending request for url (https://sepolia.base.org/)
   2: operation timed out

(the env does not have access to the internet)

Additional context

No response