Use heavy-check and heavy-x next to "Accept" and "Raise Concern" Audit actions

Summary: Mark these actions with the same markers we use in Differential.

Test Plan: {F12094}

Reviewers: csilvers, jungejason, btrahan

Reviewed By: csilvers

CC: aran

Maniphest Tasks: T1289

Differential Revision: https://secure.phabricator.com/D2601