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/BLASTBufferQueue_test.cpp b/libs/gui/tests/BLASTBufferQueue_test.cpp
index e184c7f..a87ccd6 100644
--- a/libs/gui/tests/BLASTBufferQueue_test.cpp
+++ b/libs/gui/tests/BLASTBufferQueue_test.cpp
@@ -403,7 +403,7 @@
     int32_t finalCropSideLength = bufferSideLength / 2;
 
     auto bg = mClient->createSurface(String8("BGTest"), 0, 0, PIXEL_FORMAT_RGBA_8888,
-                                     ISurfaceComposerClient::eFXSurfaceColor);
+                                     ISurfaceComposerClient::eFXSurfaceEffect);
     ASSERT_NE(nullptr, bg.get());
     Transaction t;
     t.setLayerStack(bg, 0)