Show protection hierarchy in the protection area

``` yaml
# Ticket imported from Trac
```

In the protection area for an event/session/contribution/etc... it should be specified where the "protection status" of the object is being inherited from. i.e.: ''Event 'AVC Section Meeting' is private, through inheritance from category 'IT Department'' ' .
Additionally, it could be interesting to show not only the list of people/groups that are being granted direct access to the event (for display/modification), but as well those that are inherited from the hierarchy, along with indication of their 'source'. i.e. ''Pedro Ferreira has management rights over 'AVC Section Meeting', inherited from 'AVC Section'''

The issue names the protection area for events, sessions, contributions, and related objects, but no files or tests. Start by locating that area and the hierarchy-based protection and access inheritance logic; done means showing each object's protection source and inherited people or groups with their source.

Written by the indexing model from the issue text.