[graphite] Add colorspace conversion to ImageShader

Bug: b/239959460
Change-Id: Iebf08af6ebdc622701337a7b160d74d33ba54172
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/625678
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: James Godfrey-Kittle <jamesgk@google.com>
9 files changed