Add 'viewer' to some Remarkup callsites

Summary:
I want to implement a `{P123}` rule to embed pastes, but we need viewers everywhere before it will work with privacy.

This is not exhaustive; many Remarkup callsites haven't been converted to `PhabricatorMarkupInterface` yet.

Test Plan: Looked at Maniphest, Differential, Diffusion, Phriction; added markup, made edits and hit previews.

Reviewers: vrana, btrahan

Reviewed By: vrana

CC: aran

Differential Revision: https://secure.phabricator.com/D3428

src/applications/phriction/controller/PhrictionDocumentController.php

@@ -158,7 +158,7 @@ final class PhrictionDocumentController
 
       $doc_status = $document->getStatus();
       if ($doc_status == PhrictionDocumentStatus::STATUS_EXISTS) {
-        $core_content = $content->renderContent();
+        $core_content = $content->renderContent($user);
       } else if ($doc_status == PhrictionDocumentStatus::STATUS_DELETED) {
         $notice = new AphrontErrorView();
         $notice->setSeverity(AphrontErrorView::SEVERITY_NOTICE);