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/ServerCapabilities/Workspace.cs

@@ -0,0 +1,118 @@
+//
+// 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 Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+
+namespace Microsoft.SqlTools.DataProtocol.Contracts.ServerCapabilities
+{
+    public class WorkspaceCapabilities
+    {
+        /// <summary>
+        /// Options specific to workspace folders the server supports
+        /// </summary>
+        public WorkspaceFolderCapabilities WorkspaceFolders { get; set; }
+    }
+    
+    public class WorkspaceFolderCapabilities
+    {
+        /// <summary>
+        /// Whether or not the server supports multiple workspace folders
+        /// </summary>
+        public bool? Supported { get; set; }
+        
+        /// <summary>
+        /// Whether the server wants to receive workspace folder change notifications
+        /// </summary>
+        /// <remarks>
+        /// If a string is provided, the string is treated as an ID under which the notification is
+        /// registered on the client side. The ID can be used to unregister for these events using
+        /// the client/unregisterCapability request
+        /// </remarks>
+        public WorkspaceChangeNotification ChangeNotifications { get; set; }
+    }
+
+    [JsonConverter(typeof(WorkspaceChangeNotificationJsonConverter))]
+    public class WorkspaceChangeNotification
+    {
+        public bool BooleanValue { get; }
+        
+        public string UnregisterId { get; }
+
+        private WorkspaceChangeNotification(bool booleanValue, string unregisterId)
+        {
+            BooleanValue = booleanValue;
+            UnregisterId = unregisterId;
+        }
+
+        /// <summary>
+        /// Indicates that this server can accept notifications that the workspace has changed
+        /// </summary>
+        public static WorkspaceChangeNotification True => new WorkspaceChangeNotification(true, null);
+
+        /// <summary>
+        /// Indicates that this server cannot accept notifications that the workspace has changed
+        /// </summary>
+        public static WorkspaceChangeNotification False => new WorkspaceChangeNotification(false, null);
+
+        /// <summary>
+        /// Indicates that this server can accept notifications that the workspace has changed but
+        /// reserves the right to unsubscribe from receiving workspace change notifications
+        /// </summary>
+        /// <param name="unregisterId">ID to use when unregistering for workspace change notifications</param>
+        public static WorkspaceChangeNotification WithId(string unregisterId)
+        {
+            return unregisterId == null ? null : new WorkspaceChangeNotification(true, unregisterId);
+        }
+    }
+    
+    internal class WorkspaceChangeNotificationJsonConverter : JsonConverter
+    {
+        public override bool CanRead => true;
+        public override bool CanWrite => true;
+
+        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
+        {           
+            if (value == null)
+            {
+                writer.WriteNull();
+                return;
+            }
+
+            WorkspaceChangeNotification castValue = (WorkspaceChangeNotification) value;
+            if (castValue.UnregisterId != null)
+            {
+                writer.WriteValue(castValue.UnregisterId);
+            }
+            else
+            {
+                writer.WriteValue(castValue.BooleanValue);
+            }
+        }
+
+        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
+        {
+            JToken jToken = JToken.Load(reader);
+            if (jToken.Type == JTokenType.Null)
+            {
+                return null;
+            }
+            if (jToken.Type == JTokenType.Boolean)
+            {
+                return jToken.Value<bool>()
+                    ? WorkspaceChangeNotification.True
+                    : WorkspaceChangeNotification.False;
+            }
+
+            return WorkspaceChangeNotification.WithId(jToken.Value<string>());
+        }
+
+        public override bool CanConvert(Type objectType)
+        {
+            return objectType == typeof(WorkspaceChangeNotificationJsonConverter);
+        }
+    }
+}