The external project is effectively abandoned. Fork and move it in-tree
for easier maintenance and Python 3 migration.

Bug: chromium:1296209
Change-Id: I4ff97749acb2895bd8433c08b2a4ff109c90cda2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3475086Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79240}