[skottie] Cleanup: split off layers into own CUs

TBR=
Change-Id: Ia6c27cca33f9dc8f242a50e624341dd0b465b380
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/224738
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>
diff --git a/public.bzl b/public.bzl
index 3df6fc9..203a66e 100644
--- a/public.bzl
+++ b/public.bzl
@@ -704,6 +704,8 @@
             "modules/skottie/src/*.h",
             "modules/skottie/src/effects/*.cpp",
             "modules/skottie/src/effects/*.h",
+            "modules/skottie/src/layers/*.cpp",
+            "modules/skottie/src/layers/*.h",
             "modules/skottie/src/text/*.cpp",
             "modules/skottie/src/text/*.h",
         ],