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/SqlConnectionFactory.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 System.Data.Common;
+using Microsoft.SqlTools.CoreServices.Connection.ReliableConnection;
+
+namespace Microsoft.SqlTools.CoreServices.Connection
+{
+    /// <summary>
+    /// Factory class to create SqlClientConnections
+    /// The purpose of the factory is to make it easier to mock out the database
+    /// in 'offline' unit test scenarios.
+    /// </summary>
+    public class SqlConnectionFactory : ISqlConnectionFactory
+    {
+        /// <summary>
+        /// Creates a new SqlConnection object
+        /// </summary>
+        public DbConnection CreateSqlConnection(string connectionString)
+        {
+            RetryPolicy connectionRetryPolicy = RetryPolicyFactory.CreateDefaultConnectionRetryPolicy();
+            RetryPolicy commandRetryPolicy = RetryPolicyFactory.CreateDefaultConnectionRetryPolicy();
+            return new ReliableSqlConnection(connectionString, connectionRetryPolicy, commandRetryPolicy);
+        }
+    }
+}