Fix screenshot crash with long video title, iina#3334

This commit will:
- Extend URL with a new optional computed property, creationDate
- Change the method Utility.getLatestScreenshot to use the array max method
  to find the latest screenshot file

iina/Extensions.swift

@@ -451,6 +451,10 @@ extension NSMenuItem {
 
 
 extension URL {
+  var creationDate: Date? {
+     (try? resourceValues(forKeys: [.creationDateKey]))?.creationDate
+   }
+
   var isExistingDirectory: Bool {
     return (try? self.resourceValues(forKeys: [.isDirectoryKey]))?.isDirectory ?? false
   }

iina/Utility.swift

@@ -467,17 +467,8 @@ class Utility {
       at: folder,
       includingPropertiesForKeys: [.creationDateKey],
       options: .skipsSubdirectoryDescendants),
-      var latestFile = contents.first else { return nil }
-
-    var latestDate = Date.distantPast
-
-    for file in contents {
-      if let date = try? file.resourceValues(forKeys: [.creationDateKey]).creationDate, date > latestDate {
-        latestDate = date
-        latestFile = file
-      }
-    }
-    return latestFile
+          !contents.isEmpty else { return nil }
+    return contents.max { a, b in a.creationDate! < b.creationDate! }
   }
 
   // MARK: - Util classes