Use PHUIDocumentProView in Phame

Summary: Updates "View Post" to use PHUIDocumentViewPro, updates calls to newPage and other minor modernizations. Edit Page updated to show proper document display as well. Ref T9545

Test Plan:
Write a blog post, edit it.

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Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T9545

Differential Revision: https://secure.phabricator.com/D14415