Introduce "arc inspect" and some of the new ref/hardpoint classes

Summary:
Ref T11968. Inches toward the new ref/hardpoint code by introducing the modern refs as "RefPro" objects and supporting an "arc inspect <object>" to load objects and hardpoints.

This doesn't impact any existing runtime behavior.

Test Plan: Ran "arc inspect [--all] commit(...)", got hardpoint queries and yield-based data fetching.

Maniphest Tasks: T11968

Differential Revision: https://secure.phabricator.com/D21078