[Library] iTunes library (#5)

This PR contains the work done to implement the `iTunesService` service that fetches the reviews from the **Apple App Store**.

Reviewed-on: rock-n-code/app-reviews#5
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

Libraries/Foundation/Kit/Sources/Extensions/URLSessionConfiguration+Constants.swift

@@ -0,0 +1,22 @@
+//
+//  URLSessionConfiguration+Constants.swift
+//  ReviewsFoundationKit
+//
+//  Created by Javier Cicchelli on 17/03/2024.
+//  Copyright © 2024 Röck+Cöde VoF. All rights reserved.
+//
+
+import Foundation
+
+extension URLSessionConfiguration {
+    
+    // MARK: Constants
+    public static let mock = {
+        let configuration: URLSessionConfiguration = .ephemeral
+        
+        configuration.protocolClasses = [MockURLProtocol.self]
+        
+        return configuration
+    }()
+    
+}