Expose parent node path of tree node (#1949)

* expose parent node path

* add comments

src/Microsoft.SqlTools.ServiceLayer/ObjectExplorer/Contracts/NodeInfo.cs

@@ -25,6 +25,12 @@ namespace Microsoft.SqlTools.ServiceLayer.ObjectExplorer.Contracts
         /// </summary>
         public string NodePath { get; set; }
 
+        /// <summary>
+        /// The path of the parent node. This is going to be used by the client side to determine the parent node.
+        /// We are not referencing the parent node directly because the information needs to be passed between processes.
+        /// </summary>
+        public string ParentNodePath { get; set; }
+
         /// <summary>
         /// The type of the node - for example Server, Database, Folder, Table
         /// </summary>