Pass in a SkColorType into SkImage_Gpu ctor.

This allows us to get rid of using the GrPixelConfig on proxy to create
the SkColorType

Bug: skia:6718
Change-Id: I1758b79152fa1e8a1796e55d19f5e8ca0b0e8b7b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/264396
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
10 files changed