[graphite][viewer] Wire up Dawn Vulkan on Unix and D3D12 on Windows

Bug: skia:13804
Change-Id: Ib6ab31542c8646d1f2d936df6359daf74fb03be2
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/601236
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
Auto-Submit: Peng Huang <penghuang@chromium.org>
10 files changed