This allows us to migrate PRESUBMIT.py files over to pylint-2.6 bit by
bit. It also allows us to support and upgrade pylint to newer versions
in the future.

Bug: 1221143
Fixed: 1221143
Change-Id: I9af96f5f06caf48e9923ad5fae75b98a0a7aeb49
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2994723
Commit-Queue: Peter Wen <wnwen@chromium.org>
Auto-Submit: Peter Wen <wnwen@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@google.com>