Use non-pixmap colorful icons from the icon theme in settings window's sidebar
Summary:
This patch changes the icons in the settings' window's sidebar to be all colorful, in
conformance with T10165 specifically, and the new Goal: Consistency goal more generally.
It also cleans up the code a tiny bit by using built-in constructor functionality to set
icons from the icon theme rather than leaving the icon blank in the constructor and then
setting it later.
Test Plan:
Before:
After:
Reviewers: VDG, KDE Partition Manager, stikonas, ndavis
Reviewed By: VDG, KDE Partition Manager, stikonas, ndavis
Maniphest Tasks: T10165
Differential Revision: https://phabricator.kde.org/D24272