Allow "arc browse" to browse objects

Summary: Ref T5781. This implements arc browse T234, for any monogrammed object.

Test Plan:

• Ran arc browse T234 outside of a working copy (does not require repository API).
• Ran arc browse T234 in a working copy, got task.
• Ran arc browse PATH in a working copy.
• Ran arc browse nonpath with and without --force.

Reviewers: csilvers, btrahan

Reviewed By: btrahan

Subscribers: epriestley, spicyj

Maniphest Tasks: T5781

Differential Revision: https://secure.phabricator.com/D10140