Unlike all other Skottie effects, motion blur requires sampling at multiple
points on the timeline.
To support this:
1) Introduce MotionBlurEffect - a custom SG render node which can drive
the timeline of its subtree using an sksg::Animator.
2) Introduce MotionBlurController to swap for a regular LayerController
when needed. MotionBlurController dispatches time ticks to
MotionBlurEffect instead of directly to the layer animators.
The actual motion blur impl is based on
https://skia-review.googlesource.com/c/skia/+/221416.
Motion blur requires Lottie files exported with this BodyMovin patch:
https://github.com/bodymovin/bodymovin-extension/pull/15
Change-Id: I075e101ea91ec9aa300bac35ee810fd539f1aced
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/225416
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
