Add see unread only filteration in the Inbox

[elatif2020]

Add this button (maybe we will change icon) in the Inbox next to the plus button that can be activated (similar to the follow star in the mobile chat)

once active user should see the list we have in the url /inbox?unread=true
if the list is empty we should change the placeholder text to "Hurry! No unread items in your inbox :-)"

see design

[elatif2020]

We disabled this feature for now #2336