Add checkbox for admin users to select if budget results and stats are public

[MariaCheca]

Context

Currently a budget's results and stats are public based on the phase attribute and admins can't decide when it goes public.

What

There's needed a checkbox in a budget's admin panel to select if results and stats are available for the public or not, despite the phase the budget has in that moment.

[raul-fuentes]

I'll do this one,
The check box overrides the actual phase based system or replaces it?