[graphite] Consolidate ordering constraints into DrawOrder type

Bug: skia:12466
Change-Id: I734c3a9595948dfb74f8ec72684183fe743bfefb
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/462883
Auto-Submit: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
10 files changed