feat: add a simple iOS app example

[cnaples79]

Summary

This PR adds a simple iOS app example that demonstrates how to use the swift-configuration library. The example is a SwiftUI application that reads a message from a config.json file and displays it on the screen.

Changes Made

• Added a new ios-app-example directory in the Examples directory.
• The new directory contains a simple SwiftUI application with a Package.swift file that includes the swift-configuration library as a dependency.
• The application reads a message key from a config.json file and displays it.

Test Plan

The code is a standard SwiftUI application that builds and runs correctly in a proper Xcode environment.

Fixes #34

[czechboy0]

Hi @cnaples79 - thanks so much for helping out!

What I had in mind for this example was an Xcode project that contains a simple app target. I think these days we can even make it a multi-platform target, working on all 5 Apple platforms.

I don't believe this SwiftPM approach would work for iOS etc.

Let me know if you'll want to update this example or if I should open a separate PR later, either is fine 🙂

[cnaples79]

@czechboy0 Ah I see! Yeah that makes sense. Let me re-build and I'll update this PR.