Add User-Agent to request

We generate a User-Agent for the platform we are running on and add it to the URLTester requests and also to MPV and AVPlayer

Shared/UserAgentManager.swift

@@ -0,0 +1,28 @@
+import Logging
+import WebKit
+
+final class UserAgentManager {
+    static let shared = UserAgentManager()
+
+    private(set) var userAgent: String
+    private var webView: WKWebView?
+
+    private init() {
+        // In case an error occurs while retrieving the actual User-Agent,
+        // we set a default User-Agent value that represents a commonly used User-Agent.
+        userAgent = "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)"
+
+        webView = WKWebView()
+        webView?.evaluateJavaScript("navigator.userAgent") { [weak self] result, _ in
+            if let userAgent = result as? String {
+                DispatchQueue.main.async {
+                    self?.userAgent = userAgent
+                    Logger(label: "stream.yattee.userAgentManager").info("User-Agent: \(userAgent)")
+                    print("User-Agent updated: \(userAgent)")
+                }
+            } else {
+                Logger(label: "stream.yattee.userAgentManager").warning("Failed to update User-Agent.")
+            }
+        }
+    }
+}