[sddm-theme/lock screen] Use QQC2 for the clock labels
This patch replaces the PlasmaComponents labels in Clock.qml with QQC2 ones. This resolves the issue of the clock letters/numbers getting clipped.
Before and after
Subscribers: mart, davidedmundson, plasma-devel
Maniphest Tasks: T10325
Differential Revision: https://phabricator.kde.org/D19647