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

.gitmodules

@@ -1,3 +1,6 @@
 [submodule "lib/forge-std"]
 	path = lib/forge-std
 	url = https://github.com/foundry-rs/forge-std
+[submodule "lib/aave-helpers"]
+	path = lib/aave-helpers
+	url = https://github.com/marsfoundation/aave-helpers

foundry.toml

@@ -2,5 +2,10 @@
 src = "src"
 out = "out"
 libs = ["lib"]
+remappings = [
+    'aave-helpers/=lib/aave-helpers/src/',
+    'solidity-utils/=lib/aave-helpers/lib/solidity-utils/src/',
+    'aave-address-book/=lib/aave-helpers/lib/aave-address-book/src'
+]
 
 # See more config options https://github.com/foundry-rs/foundry/tree/master/config

src/dependencies/AddressAliasHelper.sol

@@ -0,0 +1,29 @@
+// Copyright 2021-2022, Offchain Labs, Inc.
+// For license information, see https://github.com/nitro/blob/master/LICENSE
+// SPDX-License-Identifier: BUSL-1.1
+
+pragma solidity ^0.8.0;
+
+library AddressAliasHelper {
+    uint160 internal constant OFFSET = uint160(0x1111000000000000000000000000000000001111);
+
+    /// @notice Utility function that converts the address in the L1 that submitted a tx to
+    /// the inbox to the msg.sender viewed in the L2
+    /// @param l1Address the address in the L1 that triggered the tx to L2
+    /// @return l2Address L2 address as viewed in msg.sender
+    function applyL1ToL2Alias(address l1Address) internal pure returns (address l2Address) {
+        unchecked {
+            l2Address = address(uint160(l1Address) + OFFSET);
+        }
+    }
+
+    /// @notice Utility function that converts the msg.sender viewed in the L2 to the
+    /// address in the L1 that submitted a tx to the inbox
+    /// @param l2Address L2 address as viewed in msg.sender
+    /// @return l1Address the address in the L1 that triggered the tx to L2
+    function undoL1ToL2Alias(address l2Address) internal pure returns (address l1Address) {
+        unchecked {
+            l1Address = address(uint160(l2Address) - OFFSET);
+        }
+    }
+}