In Herald, save applied transaction PHIDs in the transcript and display them in the UI

Summary:
Ref T13283. Since D14575, we already pass applied transactions to Herald, but they exist only as a backwards compatibility layer and have no upstream callsites.

Save the applied transaction PHIDs as part of the object transcript, and show them in the UI.

Test Plan:

• Viewed a modern transcript, saw a list of transactions.
• Viewed an older transcript, saw nothing (since there were no transactions in the transcript).

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13283

Differential Revision: https://secure.phabricator.com/D20518