[skottie] Add support for pre-decoding images at load time

Some animations use humongous images which thrash Skia's resource caches
at raster time.

To avoid that, we can

1) force decoding upfront, when the animation is loaded

2) clamp the image size to something reasonable (2K^2)

Add a flag to support this operation mode, and enable for Skottie/WASM.

Change-Id: Id2f127a5200b812b87e588904393d82c80452aa1
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/206179
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
3 files changed