Implement query and policy rules for subprojects
Ref T10010. This implements technical groundwork for subprojects. Specifically, it implements policy rules like Phriction:
- to see a project, you must be able to see all of its parents (and the project itself).
- you can edit a project if you can edit any of its parents (or the project itself).
To facilitiate this, we load all project ancestors when querying projects so we can do the view/edit checks.
This does NOT yet implement:
- proper membership rules for these projects (up next);
- any kind of UI to let users create subprojects.
- Added unit tests.
- Executed unit tests.
- Browsed Projects (no change in behavior is expected).
Reviewed By: chad
Maniphest Tasks: T10010
Differential Revision: https://secure.phabricator.com/D14861