Hide restore data preview from technical staff

Currently when somebody runs a restore, they potentially have access to all data within the backup, including sensitive documents and emails. While they need to be able to read metadata (name, location, email subject and headers, etc) they should not be able to view the content by default.

Idea is for all accounts (except possibly the master admin account) have a default setting to hide previews. Only the master admin can change this setting.

We need to test this functionally to ensure hiding the preview doesn't impede the restore process.

Also suggest we call this out in documentation so that end users can manage this from day one, instead of getting a rude shock when they discover it.