Make restricted objects in commit messages work more consistently with the web UI

Summary:
Fixes T11344. In the web UI, if a field like "Subscribers" on an object (like a task) contains values you don't have permission to see, you see tokens for them (like "Restricted Project") but not their names.

Make commit messages work the same way: you see the PHID, and can remove it or leave it there, but can't see the underlying name.

(We have to render an actual PHID rather than just "Restricted Thing" because we have to be able to figure out what edit the user is actually trying to make.)

Test Plan: Interacted with a revision via the CLI that had project reviewers I couldn't see.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T11344

Differential Revision: https://secure.phabricator.com/D17124