Make Harbormaster input and output artifacts more explicit
Ref T1049. In Harbormaster, build steps may have various inputs (like a host they should run on) and outputs (like a reference to an uploaded file).
- Currently, inputs aren't defined anywhere (except implicitly at runtime).
- Instead, define inputs explicitly.
- Currently, outputs are defined in a way that loses information when misconfigured (the keys will collide).
- Instead, define inputs and outputs so they work whether a step is configured correctly or not.
- Currently, there's no simple way to see a step's inputs and outputs.
- Add some UI for this.
- Currently, reordering steps has some surprising side effects.
- Instead of invalidating steps after reordering them, validate them at display time and warn the user.
Reviewed By: btrahan
Subscribers: epriestley, chad
Maniphest Tasks: T1049
Differential Revision: https://secure.phabricator.com/D8599