refactor: improved type safety of platformConfig in createRun function

[hoonjoo-park]

Summary:

I improved type safety of platformConfig in createRun function. and removed unnecessary optional chaining of the platformConfig.
(code is located in cli-platform-apple/src/commands/runCommand/createRun.ts)

before I modified type of platformConfig, we couldn't infer that platformConfig could be undefined.
so, I added undefined type to platformConfig as optional.

Additionally, there was unnecessary optional chaining, so I removed it.

// * already checked if platformConfig is 'undefined'.
if (
  platformConfig === undefined ||
  supportedPlatforms[platformName] === undefined
) {
  throw new CLIError(
    `Unable to find ${platformReadableName} platform config`,
  );
}

//  * as far as I see, we don't need optional chaining in here
if (platformConfig?.automaticPodsInstallation || args.forcePods) {
  const isAppRunningNewArchitecture = platformConfig?.sourceDir
    ? await getArchitecture(platformConfig.sourceDir)
    : undefined;

  await resolvePods(ctx.root, ctx.dependencies, platformName, {
    forceInstall: args.forcePods,
    newArchEnabled: isAppRunningNewArchitecture,
  });

  installedPods = true;
}

Test Plan:

We need to check that the function is working properly, even if we put a platformName that is invalid.

Checklist

• Documentation is up to date to reflect these changes.
• Follows commit message convention described in CONTRIBUTING.md

[szymonrybczak]

Thanks! 👍