SF: Populate RE layer settings from layer snapshot and CE layer state

Make it easier to break FE dependencies to CE by populating
RE layer settings from a layer snapshot and CE layer composition state.

Test: presubmit
Test: go/wm-smoke
Bug: 238781169

Change-Id: I92bdc0a0f605c13e2dc1465c8d1ddfd17e554633
diff --git a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
index 983fac2..2c9c451 100644
--- a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
+++ b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
@@ -285,7 +285,7 @@
                                        const sp<NativeHandle>& sidebandStream) {
         layer->mDrawingState.sidebandStream = sidebandStream;
         layer->mSidebandStream = sidebandStream;
-        layer->editCompositionState()->sidebandStream = sidebandStream;
+        layer->editLayerSnapshot()->sidebandStream = sidebandStream;
     }
 
     void setLayerCompositionType(const sp<Layer>& layer,