use HttpClient to replace WebClient

Author: kasperk81

src/System.Windows.Forms/src/System/Windows/Forms/Controls/PictureBox/PictureBox.cs

@@ -7,7 +7,6 @@
 using System.Net;
 using System.Runtime.InteropServices;
 using System.Windows.Forms.Layout;
-using System.Windows.Forms.Primitives;
 
 namespace System.Windows.Forms;
 
@@ -26,6 +25,9 @@ public partial class PictureBox : Control, ISupportInitialize
         !AppContext.TryGetSwitch("System.Windows.Forms.PictureBox.UseWebRequest", out bool useWebRequest)
         || useWebRequest;
 
+    private static readonly HttpClient s_httpClient = !LocalAppContextSwitches.ServicePointManagerCheckCrl ? new() :
+        new(new HttpClientHandler { CheckCertificateRevocationList = true });
+
     /// <summary>
     ///  The type of border this control will have.
     /// </summary>
@@ -464,23 +466,26 @@ public void Load()
         try
         {
             DisposeImageStream();
-            if (UseWebRequest())
+            Uri uri = CalculateUri(_imageLocation);
+            if (uri.IsFile)
             {
-                LoadImageViaWebClient();
+                _localImageStreamReader = new StreamReader(uri.LocalPath);
+                Image img = Image.FromStream(_localImageStreamReader.BaseStream);
+                InstallNewImage(img, ImageInstallationType.FromUrl);
             }
-            else
+            else if (UseWebRequest())
             {
-                Uri uri = CalculateUri(_imageLocation);
-                if (uri.IsFile)
+                // Run async operation synchronously to avoid blocking UI thread and potential deadlocks.
+                Task.Run(async () =>
                 {
-                    _localImageStreamReader = new StreamReader(uri.LocalPath);
-                    Image img = Image.FromStream(_localImageStreamReader.BaseStream);
+                    _uriImageStream = await s_httpClient.GetStreamAsync(uri).ConfigureAwait(false);
+                    Image img = Image.FromStream(_uriImageStream);
                     InstallNewImage(img, ImageInstallationType.FromUrl);
-                }
-                else
-                {
-                    throw new NotSupportedException(SR.PictureBoxRemoteLocationNotSupported);
-                }
+                }).GetAwaiter().GetResult();
+            }
+            else
+            {
+                throw new NotSupportedException(SR.PictureBoxRemoteLocationNotSupported);
             }
         }
         catch