K3.0 + : Attachment icon is displayed without attachments #2387

This the proposition from jelle in order to replace ths PR : https://github.com/Kunena/Kunena-Forum/pull/2463

I have merged in my branch jelle PR but i wasn't able to delete obsolete commits, so i have re-done this one and it fixes teh followings : 

- delete attachments in backend File Manager
- delete attachments in frontend (Profile) File Manager