User Admin: add and implement a privacyOptionVisibility setting

[SKuipers]

Adds a new setting to User Admin, privacyOptionVisibility, that controls whether or not the privacy options are displayed to users in the data updater and the application form. Also refactors the process page of User Settings as a side-effect of making these changes.

Motivation and Context Some schools may wish to offer privacy options, internally, while not making these options selectable directly by the parents, as parents can have a tendency to check all the boxes even if they don't understand what they mean.

How Has This Been Tested? Tested locally.

Screenshots

[rossdotparker]

This looks good @SKuipers , but there is a merge conflict on CHANGELOG.txt.