Wrap VAD APIs to C# (#946)

scripts/dotnet/VadModelConfig.cs

@@ -0,0 +1,35 @@
+/// Copyright (c)  2024  Xiaomi Corporation (authors: Fangjun Kuang)
+
+using System.Linq;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using System.Text;
+using System;
+
+namespace SherpaOnnx
+{
+    [StructLayout(LayoutKind.Sequential)]
+    public struct VadModelConfig
+    {
+        public VadModelConfig()
+        {
+            SileroVad = new SileroVadModelConfig();
+            SampleRate = 16000;
+            NumThreads = 1;
+            Provider = "cpu";
+            Debug = 0;
+        }
+
+        public SileroVadModelConfig SileroVad;
+
+        public int SampleRate;
+
+        public int NumThreads;
+
+        [MarshalAs(UnmanagedType.LPStr)]
+        public string Provider;
+
+        public int Debug;
+    }
+}
+