In "bin/drydock lease", take a JSON "--attributes" so we can accept complex values
Summary:
Depends on D19750. See T13210. The `bin/drydock lease` command makes it easier to request ad-hoc leases, but currently takes lease attributes in the form `--attributes x=y,a=b`.
This was okay for all leases at the time, but doesn't really work for modern WorkingCopy resources since they take a `repositories.map` which has a dictionary as a value. You can't specify that with `repositories.map=...`.
Instead, point `--attributes` at a JSON file or use `--attributes -` to read from stdin.
Test Plan: Used `--attributes` with a file and stdin to allocate working copy leases with repositories.
Reviewers: amckinley
Reviewed By: amckinley
Subscribers: PHID-OPKG-gm6ozazyms6q6i22gyam
Differential Revision: https://secure.phabricator.com/D19751