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/ConnectParamsExtensions.cs

@@ -0,0 +1,50 @@
+//
+// 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.Connection;
+
+namespace Microsoft.SqlTools.CoreServices.Connection
+{
+    /// <summary>
+    /// Extension methods to ConnectParams
+    /// </summary>
+    public static class ConnectParamsExtensions
+    {
+        /// <summary>
+        /// Check that the fields in ConnectParams are all valid
+        /// </summary>
+        public static bool IsValid(this ConnectParams parameters, out string errorMessage)
+        {
+            errorMessage = string.Empty;
+            if (string.IsNullOrEmpty(parameters.OwnerUri))
+            {
+                errorMessage = SR.ConnectionParamsValidateNullOwnerUri; 
+            }
+            else if (parameters.Connection == null)
+            {
+                errorMessage = SR.ConnectionParamsValidateNullConnection;
+            }
+            else if (!string.IsNullOrEmpty(parameters.Connection.ConnectionString))
+            {
+                // Do not check other connection parameters if a connection string is present
+                return string.IsNullOrEmpty(errorMessage);
+            }
+            else if (string.IsNullOrEmpty(parameters.Connection.ServerName))
+            {
+                errorMessage = SR.ConnectionParamsValidateNullServerName;
+            }
+            else if (string.IsNullOrEmpty(parameters.Connection.AuthenticationType) || parameters.Connection.AuthenticationType == "SqlLogin")
+            {
+                // For SqlLogin, username cannot be empty
+                if (string.IsNullOrEmpty(parameters.Connection.UserName))
+                {
+                    errorMessage = SR.ConnectionParamsValidateNullSqlAuth("UserName");
+                }
+            }
+
+            return string.IsNullOrEmpty(errorMessage);
+        }
+    }
+}