Revert "Revert "Make FP optimizations helpers use SkAlphaType not GrColorType""

This reverts commit 078e8faa26d8b1f33a92e57f587be011150d1776.

Change-Id: I67b2970584db5a1afbf9928b77c5444947ef71a3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/255897
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
59 files changed