Refactor .Net example project (#1049)

Co-authored-by: 东风破 <birdfishs@163.com>

scripts/dotnet/OfflineLMConfig.cs

@@ -1,13 +1,12 @@
+/// Copyright (c)  2023  Xiaomi Corporation (authors: Fangjun Kuang)
+/// Copyright (c)  2023 by manyeyes
 /// Copyright (c)  2024.5 by 东风破
 
-using System.Linq;
-using System.Collections.Generic;
 using System.Runtime.InteropServices;
-using System.Text;
-using System;
 
 namespace SherpaOnnx
 {
+
     [StructLayout(LayoutKind.Sequential)]
     public struct OfflineLMConfig
     {
@@ -21,4 +20,5 @@ namespace SherpaOnnx
 
         public float Scale;
     }
-}
+
+}