[FIX] website: allow to modify the visibility of a page

Now, you can define a Visibility mode between:
    Public (All poeple)
    Connected (Portal or Employee)
    Restricted Group (Has this group or is Employee)
    With Password (Know password or is Employee)
    Internal Users (Is Employee)

It is a 'fair' feature, but without really warranty that the content is
really unreadable via others methods, ...

It is more for frontend display, that real secret. Dont use this like
a keychain ;)

We only catch the visibility on the main view and not the t-call inside.

Even if it should work on controller too, it is only display now on the
page property menu. (Or on the view directly in backend)

task-2091365