Make notification icons look like bells
Summary: BUG: 384015
Test Plan:
See D23018
Reviewers: VDG, Plasma, broulik, ngraham
Reviewed By: VDG, Plasma, broulik, ngraham
Subscribers: ngraham, broulik, kde-frameworks-devel
Tags: Frameworks
Differential Revision: https://phabricator.kde.org/D23019