[graphite] Add option to specify Paint-color opacity for Precompilation

Bug: b/358074434
Change-Id: Ia0e347556f1147fbdefce6fb5bd4dd9f5d085e28
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/983539
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
3 files changed