edit/revertCell (#268)

// edit/dispose -------------------------------------------------------------------------------
export interface EditDisposeParams extends IEditSessionOperationParams { }
export interface EditDisposeResult { }

* Initial plumbing for edit/revertCell

* Implementation of revert cell in the parents of the row edit base

* Adding unit tests

src/Microsoft.SqlTools.ServiceLayer/EditData/Contracts/EditRevertCellRequest.cs

@@ -0,0 +1,26 @@
+//
+// 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;
+
+namespace Microsoft.SqlTools.ServiceLayer.EditData.Contracts
+{
+    public class EditRevertCellParams : RowOperationParams
+    {
+        public int ColumnId { get; set; }
+    }
+
+    public class EditRevertCellResult
+    {
+        public string NewValue { get; set; }
+    }
+
+    public class EditRevertCellRequest
+    {
+        public static readonly
+            RequestType<EditRevertCellParams, EditRevertCellResult> Type =
+            RequestType<EditRevertCellParams, EditRevertCellResult>.Create("edit/revertCell");
+    }
+}