Make read/write/transfer pixels functions take surface color type

Bug: skia:6718
Change-Id: I9cac1b9dc8c04969719c79b7b7ce10c18fb428d4
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/231563
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
29 files changed