Use new Notifications KCM icon in other appropriate places too
Summary: D18678 changes the Notifications KCM's icon. This patch uses that same icon in the Notifications widget in places where clicking on it will open the KCM.
Test Plan:
Reviewers: broulik, Plasma
Reviewed By: broulik, Plasma
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D18723