Add support for APNG animated image decoding. Rework `load_from_memory`
image decoding api, to handle all the image format that currently
supported.
Testing: This change should allow `apng` and `webp` format image start
moving, and should make some WPT test related to APNG pass.
Partially address: https://github.com/servo/servo/issues/37493
[wpt try
run](https://github.com/rayguo17/servo/actions/runs/15840339570)
cc @xiaochengh
Signed-off-by: rayguo17 <rayguo17@gmail.com>