EmbeddedPkg: Add DtPlatformLoaderLib gmock support

Add Google Mock Library for DtPlatformLoaderDtbLib

Signed-off-by: Jeff Brasen <jbrasen@nvidia.com>

EmbeddedPkg/Test/Mock/Library/GoogleTest/MockDtPlatformDtbLoaderLib/MockDtPlatformDtbLoaderLib.cpp

@@ -0,0 +1,13 @@
+/** @file
+  Google Test mocks for MockDtPlatformDtbLoaderLib
+
+  Copyright (c) 2023 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+  Copyright (c) 2023, Intel Corporation. All rights reserved.
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include <GoogleTest/Library/MockDtPlatformDtbLoaderLib.h>
+
+MOCK_INTERFACE_DEFINITION (MockDtPlatformDtbLoaderLib);
+
+MOCK_FUNCTION_DEFINITION (MockDtPlatformDtbLoaderLib, DtPlatformLoadDtb, 2, EFIAPI);