Replace ffi with stdJson in constructCreate2Salt function

[smol-ninja]

During our call with Rusty (from Cantina), he suggested us to avoid using ffi for the following reasons:

• Enabling ffi allows executing any arbitrary command during foundry tests. This is what enabled us to use jq cli to read value of version from package.json
• "It is generally advised to use this cheat code as a last resort, and to not enable it by default, as anyone who can change the tests of a project will be able to execute arbitrary commands on devices that run the tests" - Foundry doc

However, a safer solution is to use stdJson which allows us to read package.json as a JSON object. This is an in-build cheat code in Foundry and doesn't require us to enable ffi. It also reduces our dependency from jq cli and reduces the number of lines required to create salt.

The following function:

function constructCreate2Salt() public returns (bytes32) {
    string memory chainId = block.chainid.toString();
    string[] memory inputs = new string[](4);
    inputs[0] = "jq";
    inputs[1] = "-r";
    inputs[2] = ".version";
    inputs[3] = "./package.json";
    bytes memory result = vm.ffi(inputs);
    string memory version = string(result);
    string memory create2Salt = string.concat("ChainID ", chainId, ", Version ", version);
    console2.log("The CREATE2 salt is \"%s\"", create2Salt);
    return bytes32(abi.encodePacked(create2Salt));
}

becomes

function constructCreate2Salt() public view returns (bytes32) {
    string memory chainId = block.chainid.toString();
    string memory json = vm.readFile("package.json");
    string memory version = json.readString(".version");
    string memory create2Salt = string.concat("ChainID ", chainId, ", Version ", version);
    console2.log("The CREATE2 salt is \"%s\"", create2Salt);
    return bytes32(abi.encodePacked(create2Salt));
}

I've already implemented it in 2cc42e5 if we agree to go ahead with this.

[PaulRBerg]

This sounds like low-risk to me but happy to accept the change.

[smol-ninja]

Related PRs:

• build: replace ffi with stdJson for salt creation #907
• build: replace ffi with stdJson for salt creation v2-periphery#333