Remove support for passing data via STDIN
Summary: Ref T7674. Remove support for passing data to linters via STDIN. This functionality exists primarily for pre-receive workflows (which don't have a working copy to act on), but these workflows are going away soon.
Test Plan: arc unit
Reviewers: Blessed Reviewers, epriestley
Reviewed By: Blessed Reviewers, epriestley
Subscribers: Korvin, epriestley
Maniphest Tasks: T7674
Differential Revision: https://secure.phabricator.com/D12696