[Arbitrum][Integrate]RIP-7728

[mralj]

Integrates RIP-7728 implemented in #2 to "arbitrum-geth".

RIP-7728

This proposal introduces a new precompiled contract, L1SLOAD, that loads several storage slots from L1, requiring a contract address, storage keys, and RPC connection to L1.

Implementation details

To leverage this precompile node runner on L2; it must have the following:

1. Some Notion of latest L1 block
2. RPC connection to L1 node, preferably "fast one" since we are making L1 RPC call during EVM precompile execution.

Our rollup-geth has a flag --rollup.l1.rpc_endpoint from which it reads the URL of the required L1 RPC.
But, since Arbitrum injects geth execution client during the nitro setup, we cannot leverage this flag. I propose to extend the nitro so that:

1. It accepts the L1 RPC URL flag
2. During Nitro node setup, it establishes a connection to L1 RPC
3. It injects this connection to the evm

// In  cmd/nitro/nitro.go
client, err := ethclient.Dial(nodeConfig.Rpc.L1Url)
if err != nil {
    log.Error("Could not dial provided L1 RPC client")
    }
vm.SetVmL1RpcClient(client)

Overriding the default config

Out of the box, rollup-geth provides the following method for "dealing" with the latest L1 block:

var defaultRollupPrecompilesConfig RollupPrecompileActivationConfig = RollupPrecompileActivationConfig{
	L1SLoad: L1SLoad{
		GetLatestL1BlockNumber: LetRPCDecideLatestL1Number, // CHANGE THIS METHOD
	},
}

The code is located in core/vm/contracts_rollup_overrides. We should pass into the GetLatestL1BlockNumber appropriate method for providing the latest L1 block on the Arbitrum blockchain.

[jmederosalvarado]

lgtm