Allow logged-out users to load global preferences on installs without public viewers

Summary:
Fixes T11946. When a logged-out viewer is loading a page on a non-public install, there are two policy issues which prevent them from loading global settings:

• They can not see the Settings application itself.
• They can not see the global settings object.

Allow them to see Settings by making mandatory applications always visible. (This doesn't make any application pages public.)

Allow them to see the global settings object explicitly.

Test Plan:
Changed default language, viewed logged-out page:

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T11946

Differential Revision: https://secure.phabricator.com/D16983