Show an entry on the system tray indicator when a portal is needed
Summary: This way it's still accessible if I lose the notification somehow.
Test Plan: I don't get it when connected normally on the internet. I managed to reach the portal when on the plane.
Reviewers: Plasma, jgrulich
Reviewed By: jgrulich
Subscribers: ngraham, plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D22079