Serialize Connection String (#680)

* add string serialization

* add unadded file

* changed code to be testable, added test

* moved test to correct location

* change to send undefined rather than error if the serialization fails

* update request name

src/Microsoft.SqlTools.ServiceLayer/Connection/Contracts/BuildConnectionInfoRequest.cs

@@ -0,0 +1,19 @@
+//
+// 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.Connection.Contracts
+{
+    /// <summary>
+    /// Serialize Connection String request 
+    /// </summary>
+    public class BuildConnectionInfoRequest
+    {
+        public static readonly
+            RequestType<string, ConnectionDetails> Type =
+            RequestType<string, ConnectionDetails>.Create("connection/buildconnectioninfo");
+    }
+}