SF: Set up librenderengine_mocks

Move the existing mocks out of the unit test directory into
RenderEngine/include/renderengine/mock and RenderEngine/mock.

This allows other unit tests to easily reuse the mocks.

Change the unit test to use the new library and reference the moved
headers.

Test: atest libsurfaceflinger_unittest libcompositionengine_test
Bug: 121291683
Change-Id: I1577995e6140cb3949207c5bc746c46b7828ae19
diff --git a/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp b/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
index 02aa5ce..de52242 100644
--- a/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
+++ b/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
@@ -21,9 +21,8 @@
 
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
-
 #include <log/log.h>
-
+#include <renderengine/mock/RenderEngine.h>
 #include <ui/DebugUtils.h>
 
 #include "DisplayIdentificationTest.h"
@@ -36,7 +35,6 @@
 #include "mock/MockMessageQueue.h"
 #include "mock/MockNativeWindowSurface.h"
 #include "mock/MockSurfaceInterceptor.h"
-#include "mock/RenderEngine/MockRenderEngine.h"
 #include "mock/gui/MockGraphicBufferConsumer.h"
 #include "mock/gui/MockGraphicBufferProducer.h"
 #include "mock/system/window/MockNativeWindow.h"