[SC-102] Add Arbitrum and Optimism forwarders and executors

[barrutko]

Proposed directory structure (updated):

• src
  • dependencies
    • arbitrum
      • AddressAliasHelper.sol [governance-crosschain-bridges/contracts/dependencies/arbitrum]
      • interfaces
        • IBridge.sol [governance-crosschain-bridges/contracts/dependencies/arbitrum/interfaces]
        • IDelayedMessageProvider.sol [governance-crosschain-bridges/contracts/dependencies/arbitrum/interfaces]
        • IGasRefunder.sol [governance-crosschain-bridges/contracts/dependencies/arbitrum/libraries]
        • IInbox.sol [governance-crosschain-bridges/contracts/dependencies/arbitrum/interfaces]
        • IOwnable.sol [governance-crosschain-bridges/contracts/dependencies/arbitrum/interfaces]
        • ISequencerInbox.sol [governance-crosschain-bridges/contracts/dependencies/arbitrum/interfaces]
    • optimism
      • interfaces
        • ICrossDomainMessenger.sol [governance-crosschain-bridges/contracts/dependencies/optimism/interfaces]
        • IL2CrossDomainMessenger.sol [governance-crosschain-bridges/contracts/dependencies/optimism/interfaces]
  • executors
    • BridgeExecutorBase.sol [governance-crosschain-bridges/contracts/bridges]
    • L2BridgeExecutor.sol [governance-crosschain-bridges/contracts/bridges]
    • ArbitrumBridgeExecutor.sol [governance-crosschain-bridges/contracts/bridges]
    • OptimismBridgeExecutor.sol [governance-crosschain-bridges/contracts/bridges]
  • forwarders
    • CrosschainForwarderArbitrum.sol [aave-helpers/src/crosschainforwarders]
    • CrosschainForwarderOptimism.sol [aave-helpers/src/crosschainforwarders]
  • interfaces
    • IExecutorBase.sol [governance-crosschain-bridges/contracts//interfaces]
    • IL2BridgeExecutor.sol [governance-crosschain-bridges/contracts//interfaces]
    • IProposalGenericExecutor.sol [aave-helpers/src/interfaces]
• tests
  • mocks
    • PayloadWithEmit.sol [aave-helpers/tests/mocks]
  • ArbitrumCrosschainForwarderTest.t.sol [aave-helpers/tests/crosschainforwarders]
  • OptimismCrosschainForwarderTest.t.sol [aave-helpers/tests/crosschainforwarders]

[linear]

SC-102 Create spark-gov-relay repo

• ALso import governance L2 executor from governance-crosschain-bridges
• Copy over Optimism, Arbitrum,
  • Add Gnosis Chain, Polygon zkEVM after review

[hexonaut]

Before continuing I think this should be restructured slightly. Also there is missing newlines at EOF. You should configure Visual Studio Code or whatever your IDE is to add these automatically.

Proposed Adjustments:

• Move BridgeExecutorBase and L2BridgeExecutor into executors dir.
• Create two directories in dependencies called optimism and arbitrum to put all the chain-specific dependencies (including interfaces)
• Move interfaces/(arbitrum|optimism) into dependencies/(arbitrum|optimism)/interfaces
• Move interfaces/executors up one directory to interfaces
• Move AddressAliasHelper into dependencies/arbitrum as it's specific to Arbitrum.

[hexonaut]

Minor changes, all code matches source repos. After they are addressed this looks good for merging. I don't care too much about the state of the tests rn as they should be rewritten to be generic and use xchain-helpers instead of manually doing the message relaying in the e2e tests BGD built.

[hexonaut]

LGTM

[lucas-manuel]

LGTM, lets merge as is, going to make another ticket to investigate how to structure GovHelpers cause it looks like its needed in both spells and here