User management support classes (#1856)

* WIP

* Fix nullable warnings in UserData class

* WIP2

* WIP

* Refresh database prototype classes

* Fix some typos & merge issues

* WIP

* WIP

* WIP

* Additional updates

* Remove unneded using

src/Microsoft.SqlTools.ServiceLayer/Security/Contracts/UserRequest.cs

@@ -0,0 +1,66 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using Microsoft.SqlTools.Hosting.Protocol.Contracts;
+using Microsoft.SqlTools.ServiceLayer.Utility;
+using Microsoft.SqlTools.Utility;
+
+namespace Microsoft.SqlTools.ServiceLayer.Security.Contracts
+{    
+    /// <summary>
+    /// Create User parameters
+    /// </summary>
+    public class CreateUserParams : GeneralRequestDetails
+    {
+        public string OwnerUri { get; set; }
+
+        public UserInfo User { get; set; }
+    }
+
+    /// <summary>
+    /// Create User result
+    /// </summary>
+    public class CreateUserResult : ResultStatus
+    {
+        public UserInfo User { get; set; }        
+    }
+
+
+    /// <summary>
+    /// Create User request type
+    /// </summary>
+    public class CreateUserRequest
+    {
+        /// <summary>
+        /// Request definition
+        /// </summary>
+        public static readonly
+            RequestType<CreateUserParams, CreateUserResult> Type =
+            RequestType<CreateUserParams, CreateUserResult>.Create("objectmanagement/createuser");
+    }
+
+    /// <summary>
+    /// Delete User params
+    /// </summary>
+    public class DeleteUserParams : GeneralRequestDetails
+    {
+        public string OwnerUri { get; set; }
+
+        public string UserName { get; set; }
+    }
+
+    /// <summary>
+    /// Delete User request type
+    /// </summary>
+    public class DeleteUserRequest
+    {
+        /// <summary>
+        /// Request definition
+        /// </summary>
+        public static readonly
+            RequestType<DeleteUserParams, ResultStatus> Type =
+            RequestType<DeleteUserParams, ResultStatus>.Create("objectmanagement/deleteuser");
+    }
+}