Feature: Add access-restricted topics on forum-widget

**Community discussion about this feature (mandatory)**
Requested by CA (and should be standard by the way)

**Is your feature request related to a problem? Please describe.**
When you are connected on the home page, you can't see any topics from "Association en interne" category (nor "Administration des sites").

**Describe the solution you'd like**
Users who are also member of the association should see topics from "Association en interne" category on home page

Start by locating the home-page topic listing and the logic that filters topics by category and association membership. Verify how connected association members are identified, then confirm that authorized users see the internal category while other users do not.

Written by the indexing model from the issue text.