Allow regular (non-admin) users access to the Manage Forums page so they can
create and manage their own forums.
Things that were already working:
* The admin forum page was already anticipating regular LoginRequired credential
* Users only see their owned forums, while admins can see and manage ALL forums
Improvements made to the Forum Admin page:
* Change the title color from admin-red to user-blue.
* Add ability to search (filter) and sort the forums.
Other changes:
* Turn the Forum tab bar into a reusable component.
* Add a Search page to the forums to filter by user ID and find threads and
replies matching your search terms, with "quoted phrases" and -negation
support.
* On user profile pages, add an "Activity" box showing statistics on their
forum threads/comments, likes given/received, photo counts, etc.
* On the "Newest" and Search page for Forums: show an indicator whenever a
post includes an attached photo.
