Add a CopyDirectory helper

NAPS2.Sdk/Util/FileSystemHelper.cs

@@ -34,4 +34,38 @@ internal static class FileSystemHelper
         exception = null;
         return false;
     }
+    
+    // https://learn.microsoft.com/en-us/dotnet/standard/io/how-to-copy-directories
+    public static void CopyDirectory(string sourceDir, string destinationDir, bool recursive)
+    {
+        // Get information about the source directory
+        var dir = new DirectoryInfo(sourceDir);
+
+        // Check if the source directory exists
+        if (!dir.Exists)
+            throw new DirectoryNotFoundException($"Source directory not found: {dir.FullName}");
+
+        // Cache directories before we start copying
+        DirectoryInfo[] dirs = dir.GetDirectories();
+
+        // Create the destination directory
+        Directory.CreateDirectory(destinationDir);
+
+        // Get the files in the source directory and copy to the destination directory
+        foreach (FileInfo file in dir.GetFiles())
+        {
+            string targetFilePath = Path.Combine(destinationDir, file.Name);
+            file.CopyTo(targetFilePath);
+        }
+
+        // If recursive and copying subdirectories, recursively call this method
+        if (recursive)
+        {
+            foreach (DirectoryInfo subDir in dirs)
+            {
+                string newDestinationDir = Path.Combine(destinationDir, subDir.Name);
+                CopyDirectory(subDir.FullName, newDestinationDir, true);
+            }
+        }
+    }
 }