Give "Auth Messages" a view/detail state before users customize them
Depends on D20663. Ref T13343. Currently, if an Auth message hasn't been customized yet, clicking the message type takes you straight to an edit screen to create a message.
If an auth message has already been customized, you go to a detail screen instead.
Since there's no detail screen on the "create for the first time" flow, we don't have anywhere to put a more detailed description or a preview of a default value.
Add a view screen that works if a message is "empty" so we can add this stuff.
(The only reason we don't already have this is that it took a little work to build; this also generally improves the consistency and predictability of this interface.)
Reviewed By: amckinley
Maniphest Tasks: T13343
Differential Revision: https://secure.phabricator.com/D20664