Let everyone view Herald rules

Summary:
Ref T9410. This changes the view policy for all Herald rules to the most public policy ("All Users" for private installs, "Public" for public installs).

See T11428 for discussion of this change in greater detail. In practice, this is approximately how things work today anyway, since you can almost always see almost all of this information in transcripts.

I believe this narrower view policy is helpful in zero cases and slightly confusing or harmful in a number of reasonable cases.

Test Plan: Viewed personal, object and global rules as users who could and could not edit the rules.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T9410

Differential Revision: https://secure.phabricator.com/D16382