Add DDL SkpOnly bot

Change-Id: If9402ad5a3ae7d17221cf1bca621b8aad4d9e9d0
Reviewed-on: https://skia-review.googlesource.com/114466
Reviewed-by: Eric Boren <borenet@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
6 files changed