[skottie] Parser cleanup

Consolidate parsing utils into their own CU.

TBR=

Change-Id: Idbf6db5220135ba91df6ebefce3a241c6ec4af15
Reviewed-on: https://skia-review.googlesource.com/99721
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>
diff --git a/BUILD.gn b/BUILD.gn
index 4af4014..90a8f9a 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -1327,6 +1327,7 @@
     sources = [
       "experimental/skottie/Skottie.cpp",
       "experimental/skottie/SkottieAnimator.cpp",
+      "experimental/skottie/SkottieParser.cpp",
       "experimental/skottie/SkottieProperties.cpp",
     ]
     deps = [