Plumb sk_sp through the GrOpList class hierarchy

This is preparing the ground for having proxies be atomically reffed

Change-Id: Ice48c41120d4ec10a758f696a69028b6363e8a7e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/207762
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
11 files changed