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/ClientCapabilities/ClientCapabilities.cs

@@ -0,0 +1,28 @@
+//
+// 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.DataProtocol.Contracts.ClientCapabilities.TextDocument;
+using Microsoft.SqlTools.DataProtocol.Contracts.ClientCapabilities.Workspace;
+
+namespace Microsoft.SqlTools.DataProtocol.Contracts.ClientCapabilities
+{
+    public class ClientCapabilities
+    {   
+        /// <summary>
+        /// Any experimental client capabilities
+        /// </summary>
+        public object Experimental { get; set; } 
+    
+        /// <summary>
+        /// Text document specific client capabilities, can be null
+        /// </summary>
+        public TextDocumentCapabilities TextDocument { get; set; }
+    
+        /// <summary>
+        /// Workspace specific client capabilities, can be null
+        /// </summary>
+        public WorkspaceCapabilities Workspace { get; set; }
+    }
+}