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.DataProtocol.Contracts/Connection/ConnectionSummaryExtensions.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.DataProtocol.Contracts.Connection
+{   
+    /// <summary>
+    /// Extension methods to ConnectionSummary
+    /// </summary>
+    public static class ConnectionSummaryExtensions
+    {
+        /// <summary>
+        /// Create a copy of a ConnectionSummary object
+        /// </summary>
+        public static ConnectionSummary Clone(this IConnectionSummary summary)
+        {
+            return new ConnectionSummary()
+            {
+                ServerName = summary.ServerName,
+                DatabaseName = summary.DatabaseName,
+                UserName = summary.UserName
+            };
+        }
+    }
+}