Modernize Transaction value controller, fixing logged-out policy issue
Summary: Fixes T9869. This specific transaction endpoint was missing shouldAllowPublic(). Also modernize things a little.
Test Plan: Viewed a policy change by clicking the policy name from the transaction record on a public object while logged out.
Reviewed By: chad
Maniphest Tasks: T9869
Differential Revision: https://secure.phabricator.com/D14606