SqlCmd Connect/On Error/Include commands support (#898)

* Initial Investigation

* Working code with include, connect, on error and tests

* Adding some loc strings

* Some cleanup and more tests

* Some dummy change to trigger build

* Adding PR comments

* Addressing PR comments

src/Microsoft.SqlTools.ManagedBatchParser/BatchParser/OnErrorSqlCmdCommand.cs

@@ -0,0 +1,17 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+namespace Microsoft.SqlTools.ServiceLayer.BatchParser
+{
+    public class OnErrorSqlCmdCommand : SqlCmdCommand
+    {
+        internal OnErrorSqlCmdCommand(OnErrorAction action) : base(LexerTokenType.OnError)
+        {
+            Action = action;
+        }
+
+        public OnErrorAction Action { get; private set; }
+    }
+}