Improve Conduit type handling for *.edit endpoints

Summary:
Ref T9964. Three goals here:

  - Make it easier to supply Conduit documentation.
  - Make automatic documentation for `*.edit` endpoints more complete, particularly for custom fields.
  - Allow type resolution via Conduit types, so you can pass `["alincoln"]` to "subscribers" instead of needing to use PHIDs.

Test Plan:
  - Viewed and used all search and edit endpoints, including custom fields.
  - Used parameter type resolution to set subscribers to user "dog" instead of "PHID-USER-whatever".
  - Viewed HTTP parameter documentation.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T9964

Differential Revision: https://secure.phabricator.com/D14796

src/applications/project/engineextension/PhabricatorProjectsEditEngineExtension.php

@@ -46,19 +46,27 @@ final class PhabricatorProjectsEditEngineExtension
       ->setKey('projectPHIDs')
       ->setLabel(pht('Projects'))
       ->setEditTypeKey('projects')
-      ->setDescription(pht('Add or remove associated projects.'))
       ->setAliases(array('project', 'projects'))
       ->setIsCopyable(true)
       ->setUseEdgeTransactions(true)
-      ->setEdgeTransactionDescriptions(
-        pht('Add projects.'),
-        pht('Remove projects.'),
-        pht('Set associated projects, overwriting current value.'))
       ->setCommentActionLabel(pht('Change Projects'))
+      ->setDescription(pht('Select projects for the object.'))
       ->setTransactionType($edge_type)
       ->setMetadataValue('edge:type', $project_edge_type)
       ->setValue($project_phids);
 
+    $projects_field->setViewer($engine->getViewer());
+
+    $edit_add = $projects_field->getConduitEditType('projects.add')
+      ->setConduitDescription(pht('Add projects.'));
+
+    $edit_set = $projects_field->getConduitEditType('projects.set')
+      ->setConduitDescription(
+        pht('Set projects, overwriting current value.'));
+
+    $edit_rem = $projects_field->getConduitEditType('projects.remove')
+      ->setConduitDescription(pht('Remove projects.'));
+
     return array(
       $projects_field,
     );