[SurfaceFlinger] Add composition unit tests

Adds some simple tests to verify the hardware and software composition
of a range of layer types, using mocks to verify the right calls are
made to the HWC and RE interfaces

Test: atest libsurfaceflinger_unittest
Bug: 76421986
Bug: 76432611
Change-Id: Ic3f81008c2182048851a8ab32388e54ee815927a
diff --git a/services/surfaceflinger/tests/unittests/Android.bp b/services/surfaceflinger/tests/unittests/Android.bp
index f1f0fbf..a8b7770 100644
--- a/services/surfaceflinger/tests/unittests/Android.bp
+++ b/services/surfaceflinger/tests/unittests/Android.bp
@@ -18,6 +18,7 @@
     test_suites: ["device-tests"],
     srcs: [
         ":libsurfaceflinger_sources",
+        "CompositionTest.cpp",
         "DisplayIdentificationTest.cpp",
         "DisplayTransactionTest.cpp",
         "EventControlThreadTest.cpp",