[ReleasePR hybridkubernetes] Added async operation support for PATCH operation (#1588)

Create to sync Azure/azure-rest-api-specs#13956
[ReCreate this PR](https://github.com/azure-resource-manager-schemas/compare/master...AzureSDKAutomation:sdkAuto/hybridkubernetes?expand=1)

Author: msftbot[bot]

schemas/2021-04-01-preview/Microsoft.Kubernetes.json

@@ -120,6 +120,21 @@
           "type": "string",
           "description": "The resource id of the private link scope this connected cluster is assigned to, if any."
         },
+        "privateLinkState": {
+          "oneOf": [
+            {
+              "type": "string",
+              "enum": [
+                "Enabled",
+                "Disabled"
+              ]
+            },
+            {
+              "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
+            }
+          ],
+          "description": "Property which describes the state of private link on a connected cluster resource."
+        },
         "provisioningState": {
           "oneOf": [
             {