Add basic IdentityUpdates contract (#154)

## Resolves
#155

## tl;dr

- Adds IdentityUpdates smart contract
- Adds the contract address to the test configuration

.vscode/settings.json

@@ -8,6 +8,7 @@
   },
   // Instructions from https://github.com/segmentio/golines
   "emeraldwalk.runonsave": {
+    "shell": "bash",
     "commands": [
       {
         "match": "\\.go$",

contracts/src/IdentityUpdates.sol

@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.13;
+
+contract IdentityUpdates {
+    event IdentityUpdateCreated(
+        bytes32 inboxId,
+        bytes update,
+        uint64 sequenceId
+    );
+
+    uint64 sequenceId;
+
+    function addIdentityUpdate(bytes32 inboxId, bytes memory update) public {
+        sequenceId++;
+
+        emit IdentityUpdateCreated(inboxId, update, sequenceId);
+    }
+}

contracts/test/IdentityUpdates.t.sol

@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.13;
+
+import {Test, console} from "forge-std/Test.sol";
+import {IdentityUpdates} from "../src/IdentityUpdates.sol";
+
+contract IdentityUpdatesTest is Test {
+    IdentityUpdates public identityUpdates;
+
+    function setUp() public {
+        identityUpdates = new IdentityUpdates();
+    }
+
+    function test_AddIdentityUpdate1k() public {
+        bytes32 inboxId = bytes32(
+            0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef
+        );
+        bytes memory message = new bytes(1024);
+        for (uint256 i = 0; i < message.length; i++) {
+            message[i] = bytes1(uint8(i % 256)); // Set each byte to its index modulo 256
+        }
+
+        identityUpdates.addIdentityUpdate(inboxId, message);
+    }
+}

dev/abigen

@@ -11,8 +11,10 @@ cd contracts
 mkdir -p ../build
 forge inspect ./src/Nodes.sol:Nodes abi > ../build/Nodes.abi.json
 forge inspect ./src/GroupMessages.sol:GroupMessages abi > ../build/GroupMessages.abi.json
+forge inspect ./src/IdentityUpdates.sol:IdentityUpdates abi > ../build/IdentityUpdates.abi.json
 
 cd ..
 # Generate Go code out of the ABI files
 abigen --abi ./build/Nodes.abi.json --pkg abis --type Nodes --out ./pkg/abis/nodes.go
-abigen --abi ./build/GroupMessages.abi.json --pkg abis --type GroupMessages --out ./pkg/abis/groupMessages.go
+abigen --abi ./build/GroupMessages.abi.json --pkg abis --type GroupMessages --out ./pkg/abis/groupMessages.go
+abigen --abi ./build/IdentityUpdates.abi.json --pkg abis --type IdentityUpdates --out ./pkg/abis/identityUpdates.go

dev/contracts/deploy-local

@@ -14,4 +14,5 @@ function deploy_contract() {
 }
 
 deploy_contract src/GroupMessages.sol GroupMessages
-deploy_contract src/Nodes.sol Nodes
+deploy_contract src/Nodes.sol Nodes
+deploy_contract src/IdentityUpdates.sol IdentityUpdates