Wrap VAD APIs to C# (#946)

scripts/dotnet/SpeechSegment.cs

@@ -0,0 +1,47 @@
+/// 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
+{
+    public class SpeechSegment
+    {
+      public SpeechSegment(IntPtr handle)
+      {
+            Impl impl = (Impl)Marshal.PtrToStructure(handle, typeof(Impl));
+
+            _start = impl.Start;
+
+            unsafe
+            {
+                float* t = (float*)impl.Samples;
+                _samples = new float[impl.Count];
+                fixed (float* pTarget = _samples)
+                {
+                    for (int i = 0; i < impl.Count; i++)
+                    {
+                        pTarget[i] = t[i];
+                    }
+                }
+            }
+      }
+
+      public int _start;
+      public int Start => _start;
+
+      private float[] _samples;
+      public float[] Samples => _samples;
+
+      [StructLayout(LayoutKind.Sequential)]
+      struct Impl
+      {
+          public int Start;
+          public IntPtr Samples;
+          public int Count;
+      }
+    }
+}