Correct overbroad automatic capability grant of global settings objects
Summary:
Ref T13679. In D16983, global settings objects were given an exception to let logged-out users see them, even on installs with no "public" user role.
This exception is too broad and grants everyone all capabilities, not just "CAN_VIEW". In particular, it incorrectly grants "CAN_EDIT", so any user can edit global settings defaults.
Restrict this grant to "CAN_VIEW".
Test Plan:
- As a non-administrator, tried to edit global settings.
- Before: could.
- After: could not.
Maniphest Tasks: T13679
Differential Revision: https://secure.phabricator.com/D21811