Support TOP n When Initializing Edit Sessions (#290)

* Start of edit initialize filtering

* Implementation to utilize filtering

* Unit tests for the refactoring

* Unit tests for query construction

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

@@ -0,0 +1,18 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+namespace Microsoft.SqlTools.ServiceLayer.EditData.Contracts
+{
+    /// <summary>
+    /// Parameters for filtering a the rows in a table to make querying easier
+    /// </summary>
+    public class EditInitializeFiltering
+    {
+        /// <summary>
+        /// Limit the records queried from the database to this many. If null, all rows are returned
+        /// </summary>
+        public int? LimitResults { get; set; }
+    }
+}

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

@@ -12,6 +12,11 @@ namespace Microsoft.SqlTools.ServiceLayer.EditData.Contracts
     /// </summary>
     public class EditInitializeParams : SessionOperationParams
     {
+        /// <summary>
+        /// Filtering parameters
+        /// </summary>
+        public EditInitializeFiltering Filters { get; set; }
+
         /// <summary>
         /// The object to use for generating an edit script
         /// </summary>