Add a linter rule for inline HTML
Summary: Ref T7409. Based on InlineHTMLSniff.
Test Plan: Added unit tests.
Reviewers: #blessed_reviewers, epriestley
Reviewed By: #blessed_reviewers, epriestley
Subscribers: Korvin
Maniphest Tasks: T9140, T7409
Differential Revision: https://secure.phabricator.com/D13871