[graphite] wire up graphite dawn backend with nanobench

Bug: skia:13804
Change-Id: I4996775f0553d46f8adac3f545db3249a73c0d4a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/597023
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Auto-Submit: Peng Huang <penghuang@chromium.org>
Commit-Queue: Robert Phillips <robertphillips@google.com>
5 files changed