Add Dawn Ubuntu18 test job

Added Test-Ubuntu18-Clang-Golo-GPU-QuadroP400-x86_64-Debug-All-Dawn
to exercise the Dawn Vulkan backend.

Change-Id: I3679822a1460eda36654f99c70ba9510e394b40c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/536736
Reviewed-by: Ravi Mistry <rmistry@google.com>
Commit-Queue: Arman Uguray <armansito@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
3 files changed