This adds a visual hint (caret down) on the toggler to help the user understand that clicking on the toggler won't do something right away, but will open a menu instead
* Kept old js widget but refactored/tweak'd it with some of our new conventions
* Added a newsroom menu component extending popupmenu
* Working as in 2.7
Still todo :
* Add variables for scss file
* Use wiget variables for most of js widget
* Correctly place the popup (absolute with <> containers ? poppers.js ? )
* Intialize toggler red bubble when new messages are in
* Replace hardcoded text in usermenu with correct dict entry updated with the nb of new message
* Only allow to open the popup when ajax calls are done
