7.1 remove old autorest (#785)

* init removal

* clean up warning

* bump ver to 7.1

* fix build

* custom http client no long supported

* cleanup unused types

* fix npe

* remove service client

* modern ssl settings

* fix test

* fix client cert null

* fix ctor

* cleanup

src/KubernetesClient/Kubernetes.WebSocket.cs

@@ -1,5 +1,5 @@
 using k8s.Models;
-using Microsoft.Rest;
+using k8s.Autorest;
 using System.Net;
 using System.Net.Http;
 using System.Net.WebSockets;
@@ -237,7 +237,11 @@ namespace k8s
 
             if (this.HttpClientHandler != null)
             {
+#if NET5_0_OR_GREATER
+                foreach (var cert in this.HttpClientHandler.SslOptions.ClientCertificates.OfType<X509Certificate2>())
+#else
                 foreach (var cert in this.HttpClientHandler.ClientCertificates.OfType<X509Certificate2>())
+#endif
                 {
                     webSocketBuilder.AddClientCertificate(cert);
                 }