Add v2 of the Hosting Service and build nuget packages for it (#675)

* Port v2 of Hosting service to SqlToolsService
- Renamed project to .v2 so that existing hosted service isn't impacted
- Copied over the CoreServices project which contains ConnectionServiceCore and other reusable services for anything interacting with MSSQL
- Ported unit test project across and verified tests run.

* Nuget package support for reusable DLLs

* Use 1.1 version per Karl's suggestion

* Use correct license URL and project URL

* Use new SMO packages

src/Microsoft.SqlTools.Hosting.v2/Channels/StdioServerChannel.cs

@@ -0,0 +1,54 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System.IO;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.SqlTools.Hosting.Protocol;
+
+namespace Microsoft.SqlTools.Hosting.Channels
+{
+    /// <summary>
+    /// Provides a server implementation for the standard I/O channel.
+    /// When started in a process, attaches to the console I/O streams
+    /// to communicate with the client that launched the process.
+    /// </summary>
+    public class StdioServerChannel : ChannelBase
+    {
+        private Stream inputStream;
+        private Stream outputStream;
+
+        public override void Start()
+        {
+#if !NanoServer
+            // Ensure that the console is using UTF-8 encoding
+            System.Console.InputEncoding = Encoding.UTF8;
+            System.Console.OutputEncoding = Encoding.UTF8;
+#endif
+
+            // Open the standard input/output streams
+            inputStream = System.Console.OpenStandardInput();
+            outputStream = System.Console.OpenStandardOutput();
+
+            // Set up the reader and writer
+            MessageReader = new MessageReader(inputStream);
+            MessageWriter = new MessageWriter(outputStream);
+
+            IsConnected = true;
+        }
+
+        public override void Stop()
+        {
+            // No default implementation needed, streams will be
+            // disposed on process shutdown.
+        }
+        
+        public override Task WaitForConnection()
+        {
+            // We're always connected immediately in the stdio channel
+            return Task.FromResult(true);
+        }
+    }
+}