Improve subproject/milestone error handling for users who can't create projects
Summary:
Fixes T10357.
- Show a better (more descriptive) error message when a user who can't create projects tries to create a subproject or milestone.
- Disable the subproject actions if you don't have create permission.
All this stuff was already enforced properly: this diff doesn't make any actual policy changes, just improves the UI for users who lack permission.
Test Plan:
- As an unprivileged user (no "Can Create Projects"), tried to create a subproject or milestone.
- After patch, got a disabled action, with more specific and helpful error than before.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T10357
Differential Revision: https://secure.phabricator.com/D15274