Modernize `ArcanistCpplintLinter`.

Summary: Convert the `cpplint.py` wrapper linter to `ArcanistExternalLinter`. This is in preparation for T2039.

Test Plan: `arc unit`.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Maniphest Tasks: T2039

Differential Revision: https://secure.phabricator.com/D9033