Add Dawn/Linux/Debug build bot

Change-Id: Ib73982154ca157c87c80195547039a55aee55892
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/288128
Reviewed-by: Weston Tracey <westont@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
2 files changed