[Wilds] Allow "arc liberate" to liberate itself again

Summary:
Ref T13098. After libphutil/ and arcanist/ merged, some paths need to be adjusted. Try to organize things a little better, too.

Also, make arc liberate with no arguments just liberate all the libraries it can find.

Test Plan: Ran arc liberate and got a valid map rebuild, although I needed to apply some hacks on top of this to make the workflow reachable.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13098

Differential Revision: https://secure.phabricator.com/D19690