Give Drydock resources and leases a real "destroy" lifecycle phase

Summary: Ref T9252. Some leases or resources may need to remove data, tear down VMs, etc., during cleanup. After they are released, queue a "destroy" phase for performing teardown.

Test Plan:

• Used bin/drydock lease ... to create a working copy lease.
• Used bin/drydock release-lease and bin/drydock release-resource to release the lease and then the working copy and host.
• Saw working copy and host get destroyed and cleaned up properly.

Reviewers: hach-que, chad

Reviewed By: chad

Maniphest Tasks: T6569, T9252

Differential Revision: https://secure.phabricator.com/D14144