Make maniphest.gettasktransactions include metadata and title

Summary:
Include task title and metadata in Conduit's `maniphest.gettasktransactions` output.
This data can for example be used by IRC bots to improve their output (e.g. conditions which changes [not] to emit or text coloring based on metadata).

Upstreaming from https://phabricator.wikimedia.org/rPHABf2fd14dc1edeb41aa2874336548cfaa7fa0e87a0

NOTE: this specific API is in "frozen" status. This method is frozen and will eventually be deprecated. New code should use "transaction.search" instead.

Closes T15916

Test Plan: Call `maniphest.gettasktransactions` on a task, see two additional fields.

Reviewers: O1 Blessed Committers, valerio.bozzolan

Reviewed By: O1 Blessed Committers, valerio.bozzolan

Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Maniphest Tasks: T15916

Differential Revision: https://we.phorge.it/D25777

src/applications/maniphest/conduit/ManiphestGetTaskTransactionsConduitAPIMethod.php

@@ -69,11 +69,13 @@ final class ManiphestGetTaskTransactionsConduitAPIMethod
 
       $results[$task_id][] = array(
         'taskID'  => $task_id,
+        'title'   => (string)$transaction->getTitleForTextMail(),
         'transactionID' => $transaction->getID(),
         'transactionPHID' => $transaction->getPHID(),
         'transactionType'  => $transaction->getTransactionType(),
         'oldValue'  => $transaction->getOldValue(),
         'newValue'  => $transaction->getNewValue(),
+        'meta'      => $transaction->getMetadata(),
         'comments'      => $comments,
         'authorPHID'  => $transaction->getAuthorPHID(),
         'dateCreated' => $transaction->getDateCreated(),