Because we tend to tack // FLUTTER_NOLINT lines onto the first available line after the copyright header, and because we tend to copy existing copyright headers into newly-created files, there are very good chances that the linter opt-out comment ends up accidentally copied along with the header.

Further, it's often unclear why a given file is opted out of the linter. We should update ci/bin/lint.dart to verify that when a FLUTTER_NOLINT comment is found, it is followed by a GitHub issue URL, or we fail the lint for the file.