Add schema compare generate script operation (#787)

* add generate script operation

src/Microsoft.SqlTools.ServiceLayer/SchemaCompare/Contracts/SchemaCompareGenerateScriptRequest.cs

@@ -0,0 +1,47 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+using Microsoft.SqlServer.Dac.Compare;
+using Microsoft.SqlTools.Hosting.Protocol.Contracts;
+using Microsoft.SqlTools.ServiceLayer.TaskServices;
+using Microsoft.SqlTools.ServiceLayer.Utility;
+using System.Collections.Generic;
+
+namespace Microsoft.SqlTools.ServiceLayer.SchemaCompare.Contracts
+{
+    /// <summary>
+    /// Parameters for a schema compare generate script request.
+    /// </summary>
+    public class SchemaCompareGenerateScriptParams
+    {
+        /// <summary>
+        /// Operation id of the schema compare operation
+        /// </summary>
+        public string OperationId { get; set; }
+
+        /// <summary>
+        /// Name of target database
+        /// </summary>
+        public string TargetDatabaseName { get; set; }
+
+        /// <summary>
+        /// Gets or sets the filepath where to save the generated script
+        /// </summary>
+        public string ScriptFilePath { get; set; }
+
+        /// <summary>
+        /// Execution mode for the operation. Default is execution
+        /// </summary>
+        public TaskExecutionMode TaskExecutionMode { get; set; }
+    }
+
+    /// <summary>
+    /// Defines the Schema Compare generate script request type
+    /// </summary>
+    class SchemaCompareGenerateScriptRequest
+    {
+        public static readonly RequestType<SchemaCompareGenerateScriptParams, ResultStatus> Type =
+            RequestType<SchemaCompareGenerateScriptParams, ResultStatus>.Create("schemaCompare/generateScript");
+    }
+}