Allow "bin/drydock lease ..." to select particular blueprints with "--blueprint"
Summary: Ref T13676. See discussion in that task.
Test Plan: Tried nonsense blueprint identifiers, duplicate identifiers, incompatible identifiers, and valid identifiers. Got apparently sensible behavior in all cases.
Subscribers: PHID-OPKG-gm6ozazyms6q6i22gyam
Maniphest Tasks: T13676
Differential Revision: https://secure.phabricator.com/D21802