[graphite] Hook up Pipeline creation.

Adds in test pipeline state object creation and shader compilation
routine.

Bug: skia:12466
Change-Id: Ie8d99078a2cebf1da37576e5a50a798fc79c295b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/456472
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
8 files changed