Replace GrConstColorProcessor with a runtime FP

Change-Id: Ie36ea4d5186f6cca341efc6300b813ec8255bdbb
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/388457
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
21 files changed