add table designer handlers (#1269)

* add table designer handlers

* add comments

src/Microsoft.SqlTools.ServiceLayer/TableDesigner/Contracts/DesignerDataPropertyInfo.cs

@@ -0,0 +1,31 @@
+//
+// 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.TableDesigner.Contracts
+{
+    /// <summary>
+    /// Represents a component/property in the table designer
+    /// </summary>
+    public class DesignerDataPropertyInfo
+    {
+        /// <summary>
+        /// The name of the property
+        /// </summary>
+        public string PropertyName { get; set; }
+
+        public string ComponentType { get; set; }
+
+        /// <summary>
+        /// The name of the group the property will be placed in whe displayed in
+        /// </summary>
+        public string Group { get; set; }
+
+
+        /// <summary>
+        /// The properties of component
+        /// </summary>
+        public ComponentPropertiesBase ComponentProperties { get; set; }
+    }
+}