Rename ColorLayer to EffectLayer to handle both shadows and color fill

We want the ability for a layer to render shadows without any content.
This new layer type will be able to combine effects as needed.

Test: presubmit tests (no functional changes)
Test: go/wm-smoke
Change-Id: I8663d126a23263a3d7dc799d39a9cf44b3b6e4a0
diff --git a/libs/gui/tests/RegionSampling_test.cpp b/libs/gui/tests/RegionSampling_test.cpp
index c9de37d..dbd4ef9 100644
--- a/libs/gui/tests/RegionSampling_test.cpp
+++ b/libs/gui/tests/RegionSampling_test.cpp
@@ -183,7 +183,7 @@
         mBackgroundLayer =
                 mSurfaceComposerClient->createSurface(String8("Background RegionSamplingTest"), 0,
                                                       0, PIXEL_FORMAT_RGBA_8888,
-                                                      ISurfaceComposerClient::eFXSurfaceColor);
+                                                      ISurfaceComposerClient::eFXSurfaceEffect);
         uint32_t layerPositionBottom = 0x7E000000;
         SurfaceComposerClient::Transaction{}
                 .setLayer(mBackgroundLayer, layerPositionBottom)