[Skottie] Add raw data factory

... and funnel all existing factories through the new one.

Change-Id: I01ffb95abf178eacc0ad430e730d680800a509c7
Reviewed-on: https://skia-review.googlesource.com/145428
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
2 files changed