layernorm2d forward (#1339)

* Add layernorm2d forward

* Refind file path

* clang format

* Exclude ck_tile op from all

* use add_executable instead

* refactor layernorm2d_fwd example

---------

Co-authored-by: carlushuang <carlus.huang@amd.com>

[ROCm/composable_kernel commit: cb13839425]

include/ck_tile/core/numeric/null_type.hpp

@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2018-2024, Advanced Micro Devices, Inc. All rights reserved.
+
+#pragma once
+#include <stdint.h>
+
+namespace ck_tile {
+
+struct null_type
+{
+};
+
+} // namespace ck_tile