Provide arc linters --verbose to list all available options

Summary:
Ref T2039. I'll update the corresponding documentation.

It feels a little awkward that this is disconnected from getLinterConfigurationOptions(), but I dislike returning weird ad-hoc structures more than I dislike having two methods. Most linters don't implement either of these anyway.

Test Plan: Ran arc linters and arc linters --verbose.

Reviewers: btrahan, joshuaspence

Reviewed By: joshuaspence

Subscribers: epriestley

Maniphest Tasks: T2039

Differential Revision: https://secure.phabricator.com/D9062