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/services/surfaceflinger/Android.bp b/services/surfaceflinger/Android.bp
index 1b1e889..4ffdf97 100644
--- a/services/surfaceflinger/Android.bp
+++ b/services/surfaceflinger/Android.bp
@@ -136,7 +136,7 @@
         "BufferStateLayer.cpp",
         "ClientCache.cpp",
         "Client.cpp",
-        "ColorLayer.cpp",
+        "EffectLayer.cpp",
         "ContainerLayer.cpp",
         "DisplayDevice.cpp",
         "DisplayHardware/ComposerHal.cpp",