Renamed UnpackedPlugin class to "Plugin"

* we may re-implement "runtime" Plugins behaviour, without the need to pack the Plugins in order to use them. That way, Plugins would have PackingBehaviours and RuntimeBehaviours
CS fixes
Auth Plugin "user" service refactoring
PHP pack profile fix after "UnpackedPlugin" class renaming
User display fix
Added a "exec" alias for our Application "execFunction" method
The "utils/home breadcrumb" data is now a function instead of a var
ActionsPacker: added management of routes priorities

* As Slim Router don't allow multiple routes with the same name, we now check the action name existence before adding it to Slim
* Routes are now computed in a ActionsPacker plugin init "$app->before" function
* Routes can now have a priority