[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/iTunes/Kit/Services/iTunesService.swift

@@ -0,0 +1,43 @@
+//
+//  iTunesService.swift
+//  ReviewsiTunes
+//
+//  Created by Javier Cicchelli on 17/03/2024.
+//  Copyright © 2024 Röck+Cöde VoF. All rights reserved.
+//
+
+import Foundation
+import ReviewsFeedKit
+
+public actor iTunesService: Service {
+    
+    // MARK: Constants
+    public let configuration: ServiceConfiguration
+    public let decoder: JSONDecoder
+    public let session: URLSession
+    
+    // MARK: Properties
+    private lazy var getReviewsEndpoint: GetReviewsAPIEndpoint = {
+        .init(
+            host: configuration.host,
+            decoder: decoder,
+            session: session
+        )
+    }()
+    
+    // MARK: Initialisers
+    public init(configuration: ServiceConfiguration) {
+        self.configuration = configuration
+        self.decoder = configuration.decoder
+        self.session = .init(configuration: configuration.session)
+    }
+    
+    // MARK: Functions
+    @discardableResult public func getReviews(
+        _ input: GetReviewsInput
+    ) async throws -> GetReviewsOutput {
+        try await getReviewsEndpoint(input)
+    }
+    
+}
+