b/333952175 Fix marshalling of SendKeys parameters (#1362)

Use modified version of `IMsRdpClientNonScriptable5` interface to 
ensure proper marshalling of C array-typed parameters.

sources/Google.Solutions.Common/Interop/VariantBool.cs

@@ -0,0 +1,36 @@
+//
+// Copyright 2024 Google LLC
+//
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+// 
+//   http://www.apache.org/licenses/LICENSE-2.0
+// 
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+//
+
+namespace Google.Solutions.Common.Interop
+{
+    public static class VariantBool
+    {
+        /// <summary>
+        /// VARIANT_FALSE.
+        /// </summary>
+        public const short False = 0;
+
+        /// <summary>
+        /// VARIANT_TRUE.
+        /// </summary>
+        public const short True = -1;
+    }
+}