Pass a gerrit object instead of a git-cl ChangeList object to
PostUploadHook to remove dependency of presubmit_support in git-cl.

Requires https://skia-review.googlesource.com/c/skia/+/265209

Bug: 1042324
Change-Id: I4b20b75deb6a3d8d4caf46ca3580883699dbf707
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2008287
Auto-Submit: Edward Lesmes <ehmaldonado@chromium.org>
Reviewed-by: Anthony Polito <apolito@google.com>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>