Added local 2.5 dsm to samples in case system doesn't have it.

samples/WinForm32/DsmLoader.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+using System.Runtime.InteropServices;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace WinFormSample
+{
+  /// <summary>
+  /// For demoing loading dsm from custom path in case
+  /// it's not installed on system and can't be placed 
+  /// besides the exe.
+  /// </summary>
+  static class DsmLoader
+  {
+    static IntPtr __dllPtr;
+
+    public static bool TryUseCustomDSM()
+    {
+      if (__dllPtr == IntPtr.Zero)
+      {
+        var dll = Path.Combine(
+          Path.GetDirectoryName(Environment.ProcessPath ?? Assembly.GetExecutingAssembly().Location)!,
+          "platforms\\TWAINDSM.dll");
+
+        __dllPtr = LoadLibraryW(dll);
+      }
+      return __dllPtr != IntPtr.Zero;
+    }
+
+    [DllImport("kernel32", SetLastError = true)]
+    static extern IntPtr LoadLibraryW([MarshalAs(UnmanagedType.LPWStr)] string lpFileName);
+  }
+}