Fix title bar small icon scaling (#13787)

We weren't actually scaling the icon for the main form. In addition, we didn't have an embedded icon with multiple resolutions. This appropriately sets the right sized icon to eliminate or reduce blurring.

Author: JeremyKuhne

src/System.Windows.Forms/Resources/System/Windows/Forms/wfc.ico

@@ -4546,6 +4546,7 @@ protected virtual void OnDpiChanged(DpiChangedEventArgs e)
                     _processingDpiChanged = true;
                 }
 
+                UpdateWindowIcon(redrawFrame: true, dpi: e.DeviceDpiNew);
                 ScaleContainerForDpi(e.DeviceDpiNew, e.DeviceDpiOld, e.SuggestedRectangle);
             }
             finally
@@ -6417,12 +6418,17 @@ protected override void OnStyleChanged(EventArgs e)
     /// <summary>
     ///  Updates the window icon.
     /// </summary>
-    private unsafe void UpdateWindowIcon(bool redrawFrame)
+    private unsafe void UpdateWindowIcon(bool redrawFrame, int dpi = 0)
     {
         if (IsHandleCreated)
         {
             Icon? icon;
 
+            if (dpi == 0)
+            {
+                dpi = DeviceDpi;
+            }
+
             // Preserve Win32 behavior by keeping the icon we set NULL if
             // the user hasn't specified an icon and we are a dialog frame.
             if ((FormBorderStyle == FormBorderStyle.FixedDialog && _formState[s_formStateIconSet] == 0) || !ShowIcon)
@@ -6436,20 +6442,23 @@ private unsafe void UpdateWindowIcon(bool redrawFrame)
 
             if (icon is not null)
             {
-                if (_smallIcon is null)
+                Icon? oldSmallIcon = _smallIcon;
+
+                try
+                {
+                    _smallIcon = ScaleHelper.ScaleSmallIconToDpi(icon, dpi);
+                }
+                catch
                 {
-                    try
-                    {
-                        _smallIcon = new Icon(icon, SystemInformation.SmallIconSize);
-                    }
-                    catch
-                    {
-                    }
                 }
 
                 if (_smallIcon is not null)
                 {
                     PInvokeCore.SendMessage(this, PInvokeCore.WM_SETICON, (WPARAM)PInvoke.ICON_SMALL, (LPARAM)_smallIcon.Handle);
+                    if (oldSmallIcon is not null && oldSmallIcon.Handle != _smallIcon.Handle)
+                    {
+                        oldSmallIcon.Dispose();
+                    }
                 }
 
                 PInvokeCore.SendMessage(this, PInvokeCore.WM_SETICON, (WPARAM)PInvoke.ICON_BIG, (LPARAM)icon.Handle);