Redesign Advanced tab
Summary: This patch redesigns and modernizes the Advanced tab of SDDM's KCM.
Test Plan:
Before:
After:
Entries were still being written to /etc/sddm.conf
Reviewers: ngraham, VDG, davidedmundson
Reviewed By: ngraham, VDG
Subscribers: abetts, plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D21610