Summary:
port the fonts kcm to QML, reviving an old branch.
UI based upon M112/411
make use of the new Kirigami FormLayout
depends from D8641
Fixes T7244

Test Plan: tried all the options

Reviewers: #plasma, #vdg

Subscribers: hein, ngraham, plasma-devel

Tags: #plasma

Maniphest Tasks: T7244

Differential Revision: https://phabricator.kde.org/D8916