Add a bin/herald test ... for doing test runs via the CLI

Summary: Ref T13216. See D19666. It's currently tricky to profile Herald test runs since you have to submit a form and repeating them is a bit of a mess. Provide a simple CLI wrapper so we can use --xprofile. This is also maybe nice-to-have if we're ever debugging anything here.

Test Plan: Ran bin/herald test --object ... --type ... and got a sensible looking transcript in the UI.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13216

Differential Revision: https://secure.phabricator.com/D19806