Move unused forked code to external directory (#1192)

* Move unused forked code to external directory

* Fix SLN build errors

* Add back resource provider core since it's referenced by main resource provider project

* Update PackageProjects step of pipeline

external/Microsoft.SqlTools.Hosting.v2/Protocol/Exceptions.cs

@@ -0,0 +1,35 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System;
+using Microsoft.SqlTools.Hosting.v2;
+
+namespace Microsoft.SqlTools.Hosting.Protocol
+{
+    /// <summary>
+    /// Exception thrown when parsing a message from input stream fails.
+    /// </summary>
+    public class MessageParseException : Exception
+    {
+        public string OriginalMessageText { get; }
+
+        public MessageParseException(string originalMessageText, string errorMessage, params object[] errorMessageArgs)
+            : base(string.Format(errorMessage, errorMessageArgs))
+        {
+            OriginalMessageText = originalMessageText;
+        }
+    }
+
+    /// <summary>
+    /// Exception thrown when a handler for a given request/event method does not exist
+    /// </summary>
+    public class MethodHandlerDoesNotExistException : Exception
+    {
+        public MethodHandlerDoesNotExistException(MessageType type, string method)
+            : base(SR.HostingMethodHandlerDoesNotExist(type.ToString(), method))
+        {
+        }
+    }
+}