cc::SoftwareImageDecode: Tone map at rasterization time

Historically, tone mapping was always performed at image decode time,
for software raster and for GPU raster.

This was a very bad arrangement for GPU raster, and has been changed to
be done at raster time. Along the way, software raster got broken for
HLG and PQ images, for some formats. That didn't matter because gain map
images were much more important, and did work (in the most common
configurations).

Change software raster to perform tone mapping at raster time, like GPU
raster. This will be much more robust (and, in fact, fixes some pixel
tests that were failing, and preventing rolling out Skia's new, more
robust HLG and PQ representations). That said, this can be less
performant for HDR images that are not gainmap images with an SDR base.
This is a rare situation, so the tradeoff seems worth it.

It may be that this will be re-evaluated in the distant future. In such
a future, it is likely that caching of decode and caching of tone
mapping will be separated.

Bug: 428575083
Change-Id: I0cb156d56b9caca0e29887bd9f64421d1a0bed11
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6810445
Reviewed-by: Vasiliy Telezhnikov <vasilyt@chromium.org>
Commit-Queue: ccameron chromium <ccameron@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1495683}