Move code from header files to cpp files

Moved code from:
- shared/test/common/mocks/mock_execution_environment.h
- shared/test/common/fixtures/mock_aub_center_fixture.h

Signed-off-by: Mateusz Jablonski <mateusz.jablonski@intel.com>

opencl/test/unit_test/fixtures/multi_root_device_fixture.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2019-2021 Intel Corporation
+ * Copyright (C) 2019-2022 Intel Corporation
  *
  * SPDX-License-Identifier: MIT
  *
@@ -15,6 +15,8 @@
 #include "opencl/test/unit_test/mocks/mock_cl_device.h"
 #include "opencl/test/unit_test/mocks/mock_context.h"
 
+#include "gtest/gtest.h"
+
 namespace NEO {
 class MultiRootDeviceFixture : public ::testing::Test {
   public:

opencl/test/unit_test/fixtures/multi_tile_fixture.h

@@ -16,6 +16,8 @@
 #include "opencl/source/platform/platform.h"
 #include "opencl/test/unit_test/mocks/mock_platform.h"
 
+#include "gtest/gtest.h"
+
 struct MultiTileFixture : public ::testing::Test {
     void SetUp() override {
         ultHwConfig.useMockedPrepareDeviceEnvironmentsFunc = false;