FLEDGE: Support abort of auction with AbortController

ref: https://github.com/WICG/turtledove/issues/293

Change-Id: I0ea392c7c4816b767d9b301b305c0617d58c3977
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3805648


Reviewed-by: Matt Menke <mmenke@chromium.org>
Reviewed-by: Dominic Farolino <dom@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Maks Orlovich <morlovich@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1045867}