Allow "bin/repository thaw" to accept "--all-repositories" instead of a list of repositories

Summary:
Ref T13222. See PHI992. If you've lost an entire cluster (or have lost a device and are willing to make broad assumptions about the state the device was in) you currently have to xargs to thaw everything or do something else creative.

Since this workflow is broadly reasonable, provide an easier way to accomplish the goal.

Test Plan:

• Ran with --all-repositories, a list of repositories, both (error) and neither (error).
• Saw a helpful new list of affected repositories.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13222

Differential Revision: https://secure.phabricator.com/D19849