Implement remarkup custom control

Summary: Ref T2575. Adds "remarkup" control, which displays a remarkup control and uses the remarkup cache. Grants fields access to remarkup pipeline.

Test Plan:
{F35067}
{F35068}

Used DarkConsole to verify cache interaction with services.

Reviewers: hach-que, btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2575

Differential Revision: https://secure.phabricator.com/D5286

src/applications/maniphest/controller/ManiphestTaskDetailController.php

@@ -126,11 +126,19 @@ final class ManiphestTaskDetailController extends ManiphestController {
         $engine->addObject($xaction, ManiphestTransaction::MARKUP_FIELD_BODY);
       }
     }
-    $engine->process();
 
     $extensions = ManiphestTaskExtensions::newExtensions();
     $aux_fields = $extensions->loadFields($task, $user);
 
+    foreach ($aux_fields as $aux_field) {
+      foreach ($aux_field->getMarkupFields() as $markup_field) {
+        $engine->addObject($aux_field, $markup_field);
+        $aux_field->setMarkupEngine($engine);
+      }
+    }
+
+    $engine->process();
+
     $transaction_types = ManiphestTransactionType::getTransactionTypeMap();
     $resolution_types = ManiphestTaskStatus::getTaskStatusMap();