Add agent skills for dealing with fuzz issues

No-Try: true
Change-Id: I02e1b9dd707baa83908ffee215f79df0d9cc46d1
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1253617
Commit-Queue: Kaylee Lubick <kjlubick@google.com>
Auto-Submit: Kaylee Lubick <kjlubick@google.com>
Reviewed-by: Jorge Betancourt <jmbetancourt@google.com>