Remove AphrontPanelView from Diffusion

Summary: Removes remaining AphrontPanelView calls in Diffusion for UI Consistency.

Test Plan: Tested each page except lint details, which I couldn't quite find a path to. Everything looks right.

Reviewers: epriestley, btrahan

Reviewed By: btrahan

Subscribers: Korvin, epriestley

Maniphest Tasks: T7427

Differential Revision: https://secure.phabricator.com/D12001