adjust default `PostDeploy` script to support AWS KMS

[alvrs]

forge supports executing forge scripts via aws kms, but the current default PostDeploy scripts included in templates explicitly try to load a private key from the PRIVATE_KEY environment variable

[alvrs]

// SPDX-License-Identifier: MIT
pragma solidity >=0.8.24;

import { Script } from "forge-std/Script.sol";
import { console } from "forge-std/console.sol";
import { StoreSwitch } from "@latticexyz/store/src/StoreSwitch.sol";
import { IWorld } from "../src/codegen/world/IWorld.sol";

contract PostDeployKms is Script {
  function run(address worldAddress, address deployer) external {
    // Specify a store so that you can use tables directly in PostDeploy
    StoreSwitch.setStoreAddress(worldAddress);

    // Start broadcasting transactions from the deployer account
    vm.startBroadcast(deployer);

    // ... logic to execute

    vm.stopBroadcast();
  }
}