Add support for create, update, and delete for custom role definitions (Azure#18227)

* Implement create, update, get, and delete for Role Definitions

Author: christothes

sdk/keyvault/Azure.Security.KeyVault.Administration/CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## 4.0.0-beta.4 (Unreleased)
 
+### Added
+
+- Support in `KeyVaultAccessControlClient` to create, update, and delete custom role definitions.
 
 ## 4.0.0-beta.3 (2020-11-12)
 

sdk/keyvault/Azure.Security.KeyVault.Administration/api/Azure.Security.KeyVault.Administration.netstandard2.0.cs

@@ -0,0 +1,12 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+using Azure.Core;
+
+namespace Azure.Security.KeyVault.Administration.Models
+{
+    [CodeGenModel("DataAction")]
+    public readonly partial struct KeyVaultDataAction : IEquatable<KeyVaultDataAction>
+    { }
+}