This entails a few parts:
1. Isolating tools/skpbench/ to be used by the perf task.
2. Adding skpbench to BUILD_PRODUCTS_ISOLATE_WHITELIST
3. Add recipe commands to run skpbench. While it is conceptually similar
to nanobench, it doesn't support images nor svgs, only skps, so we don't
need to copy those to devices or bring them in via CIPD.
4. Add recipe commands to parse skpbench output and upload to Perf.
5. Update gen_tasks.go to handle skpbench jobs and tasks.
BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4551
Change-Id: I09bf0b078067279e138e95eca9316e55539ec735
Reviewed-on: https://skia-review.googlesource.com/4551
Commit-Queue: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Eric Boren <borenet@google.com>
