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.CoreServices/Connection/CancelTokenKey.cs

@@ -0,0 +1,36 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.SqlTools.DataProtocol.Contracts.Connection;
+
+namespace Microsoft.SqlTools.CoreServices.Connection
+{
+    /// <summary>
+    /// Used to uniquely identify a CancellationTokenSource associated with both
+    /// a string URI and a string connection type.
+    /// </summary>
+    public class CancelTokenKey : CancelConnectParams, IEquatable<CancelTokenKey>
+    {
+        public override bool Equals(object obj)
+        {
+            CancelTokenKey other = obj as CancelTokenKey;
+            if (other == null)
+            {
+                return false;
+            }
+
+            return other.OwnerUri == OwnerUri && other.Type == Type;
+        }
+
+        public bool Equals(CancelTokenKey obj)
+        {
+            return obj.OwnerUri == OwnerUri && obj.Type == Type;
+        }
+
+        public override int GetHashCode()
+        {
+            return OwnerUri.GetHashCode() ^ Type.GetHashCode();
+        }
+    }
+}