SkCrabbyAvifCodec: Return correct image type

Instead of always returning the image format as AVIF, return
either HEIF or AVIF depending on the actual image.

Bug: b/323753814
Change-Id: I5cd49cb1a86e7942e4e63aadae8821e863e71da3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/936936
Reviewed-by: Noelle Scobie <nscobie@google.com>
Commit-Queue: Vignesh Venkat <vigneshv@google.com>
2 files changed