Move audit rendering into SearchEngine

Summary:
Ref T4986. Updates audit.

Slightly tweaks on method visibility.

Just used a HandleQuery since we have to rebuild the whole view thing otherwise; this is an unusual case.

Test Plan:

• Checked Audit.
• Checked Feed.
• Checked Slowvote.

{F151555}

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T4986

Differential Revision: https://secure.phabricator.com/D9011