BP Nouveau: restore the Notice notification feature

[imath]

I just noticed this feature wasn't working anymore. I believe the Notifications component got some improvements with the introduction of the bp_notifications_get_grouped_notifications_for_user() function.

So the attached patch suggest to restore it. This is something I added to this template pack because Notices are displayed into the User's front-end profile and might not be seen by some users.

[imath]

Here's a screenshot of the result of the patch when a notice is published widely.

[imath]

In 13036:

BP Nouveau: include a notification to the active Site Wide Notice

When a Site Wide notice is active the BP Nouveau template pack is prepending a notification to the logged in user notifications list.

FYI: This feature was "missing in action" since the introduction of the bp_notifications_get_grouped_notifications_for_user() and its use inside the bp_notifications_get_notifications_for_user() function in replacement of bp_notifications_get_all_notifications_for_user().

Fixes #8547