NoticeMessageItem is not added to open contact list after sharing forum

To reproduce:

1. Open chat with contact A
2. Switch to forums in the sidebar
3. share a forum with contact A
4. switch back to private messages
5. notice that the chat with contact A is still open, but the info message, that the forum has been shared, is not shown
6. switch to another contact B and back to contact A, see the info message