chore: import upstream snapshot with attribution

tests/cpp_tests/test_main.cpp

@@ -0,0 +1,12 @@
+/*!
+ * Copyright (c) 2021-2026 Microsoft Corporation. All rights reserved.
+ * Copyright (c) 2021-2026 The LightGBM developers. All rights reserved.
+ * Licensed under the MIT License. See LICENSE file in the project root for license information.
+ */
+#include <gtest/gtest.h>
+
+int main(int argc, char** argv) {
+  testing::InitGoogleTest(&argc, argv);
+  testing::FLAGS_gtest_death_test_style = "threadsafe";
+  return RUN_ALL_TESTS();
+}