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.Contracts/EventType.cs

@@ -0,0 +1,33 @@
+//
+// 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.Hosting.Contracts
+{
+    /// <summary>
+    /// Defines an event type with a particular method name.
+    /// </summary>
+    /// <typeparam name="TParams">The parameter type for this event.</typeparam>
+    public class EventType<TParams>
+    {
+        /// <summary>
+        /// Gets the method name for the event type.
+        /// </summary>
+        public string MethodName { get; private set; }
+
+        /// <summary>
+        /// Creates an EventType instance with the given parameter type and method name.
+        /// </summary>
+        /// <param name="methodName">The method name of the event.</param>
+        /// <returns>A new EventType instance for the defined type.</returns>
+        public static EventType<TParams> Create(string methodName)
+        {
+            return new EventType<TParams>()
+            {
+                MethodName = methodName
+            };
+        }
+    }
+}
+

src/Microsoft.SqlTools.Hosting.Contracts/Internal/Error.cs

@@ -0,0 +1,23 @@
+//
+// 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.Hosting.Contracts.Internal
+{
+    /// <summary>
+    /// Defines the message contract for errors returned via <see cref="Microsoft.SqlTools.Hosting.Protocol.RequestContext.SendError"/>
+    /// </summary>
+    public class Error
+    {
+        /// <summary>
+        /// Error code. If omitted will default to 0
+        /// </summary>
+        public int Code { get; set; }
+
+        /// <summary>
+        /// Error message
+        /// </summary>
+        public string Message { get; set; }
+    }
+}

src/Microsoft.SqlTools.Hosting.Contracts/Internal/ExitNotification.cs

@@ -0,0 +1,16 @@
+//
+// 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.Hosting.Contracts.Internal
+{
+    /// <summary>
+    /// Defines an event that is sent from the client to notify that
+    /// the client is exiting and the server should as well.
+    /// </summary>
+    public class ExitNotification
+    {
+        public static readonly EventType<object> Type = EventType<object>.Create("exit");
+    }
+}

src/Microsoft.SqlTools.Hosting.Contracts/Internal/HostingErrorNotification.cs

@@ -0,0 +1,26 @@
+//
+// 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.Hosting.Contracts.Internal
+{
+    /// <summary>
+    /// Parameters to be used for reporting hosting-level errors, such as protocol violations
+    /// </summary>
+    public class HostingErrorParams
+    {
+        /// <summary>
+        /// The message of the error
+        /// </summary>
+        public string Message { get; set; }
+    }
+
+    public class HostingErrorNotification
+    {
+        public static readonly 
+            EventType<HostingErrorParams> Type =
+            EventType<HostingErrorParams>.Create("hosting/error");
+
+    }
+}

src/Microsoft.SqlTools.Hosting.Contracts/Internal/ShutdownRequest.cs

@@ -0,0 +1,17 @@
+//
+// 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.Hosting.Contracts.Internal
+{
+    /// <summary>
+    /// Defines a message that is sent from the client to request
+    /// that the server shut down.
+    /// </summary>
+    public class ShutdownRequest
+    {
+        public static readonly RequestType<object, object> Type = RequestType<object, object>.Create("shutdown");
+    }
+}
+

src/Microsoft.SqlTools.Hosting.Contracts/Microsoft.SqlTools.Hosting.Contracts.csproj

@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>netstandard2.0</TargetFramework>
+    <PackageDescription>
+    Defines the core messages needed for the Microsoft.SqlTools.Hosting service to communicate over the VSCode Language Server Protocol.
+    </PackageDescription>
+    <Description>$(PackageDescription)</Description>
+  </PropertyGroup>
+  <Import Project="..\sqltools.common.targets" />
+</Project>

src/Microsoft.SqlTools.Hosting.Contracts/RequestType.cs

@@ -0,0 +1,24 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System.Diagnostics;
+
+namespace Microsoft.SqlTools.Hosting.Contracts
+{
+    [DebuggerDisplay("RequestType MethodName = {MethodName}")]
+    public class RequestType<TParams, TResult>
+    {
+        public string MethodName { get; private set; }
+
+        public static RequestType<TParams, TResult> Create(string typeName)
+        {
+            return new RequestType<TParams, TResult>()
+            {
+                MethodName = typeName
+            };
+        }
+    }
+}
+