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