R1:07dc94321568

Modernize the `drydock` script

Summary: Add a bin/drydock symlink and break it into workflows. Nothing too special here.

Test Plan: Ran `bin/drydock wait-for-lease`, `bin/drydock lease`, `bin/drydock help`, etc.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2015

Differential Revision: https://secure.phabricator.com/D3867