Index Herald fields, not just actions, when identifying objects related to a particular Herald rule

Summary:
Fixes T13408. Currently, when a package (or other object) appears in a field (rather than an action), it is not indexed.

Instead: index fields too, not just actions.

Test Plan:
- Wrote a rule like "[ Affected packages include ] ...".
- Updated the search index.
- Saw rule appear on "Affected By Herald Rules" on the package detail page.

Subscribers: PHID-OPKG-gm6ozazyms6q6i22gyam

Maniphest Tasks: T13408

Differential Revision: https://secure.phabricator.com/D20795

resources/sql/autopatches/20190909.herald.01.rebuild.php

···
+<?php
+
+PhabricatorRebuildIndexesWorker::rebuildObjectsWithQuery('HeraldRuleQuery');

src/applications/herald/engineextension/HeraldRuleIndexEngineExtension.php

···
 
     $phids = array();
 
+    $fields = HeraldField::getAllFields();
+    foreach ($rule->getConditions() as $condition_record) {
+      $field = idx($fields, $condition_record->getFieldName());
+
+      if (!$field) {
+        continue;
+      }
+
+      $affected_phids = $field->getPHIDsAffectedByCondition($condition_record);
+      foreach ($affected_phids as $phid) {
+        $phids[] = $phid;
+      }
+    }
+
     $actions = HeraldAction::getAllActions();
     foreach ($rule->getActions() as $action_record) {
       $action = idx($actions, $action_record->getAction());

src/applications/herald/field/HeraldField.php

···
     return $value_type->renderEditorValue($value);
   }
 
+  public function getPHIDsAffectedByCondition(HeraldCondition $condition) {
+    $phids = array();
+
+    $standard_type = $this->getHeraldFieldStandardType();
+    switch ($standard_type) {
+      case self::STANDARD_PHID:
+      case self::STANDARD_PHID_NULLABLE:
+        $phid = $condition->getValue();
+        if ($phid) {
+          $phids[] = $phid;
+        }
+        break;
+      case self::STANDARD_PHID_LIST:
+        foreach ($condition->getValue() as $phid) {
+          $phids[] = $phid;
+        }
+        break;
+    }
+
+    return $phids;
+  }
+
   final public function setAdapter(HeraldAdapter $adapter) {
     $this->adapter = $adapter;
     return $this;