[graphite] Add commands to CommandBuffer from Tasks

Bug: skia:12466
Change-Id: I1e92dcf66c117ca351cebf20722524672c88e5cd
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/469178
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
12 files changed