[fuzzy-clock] Port configuration window to QQC2 and Kirigami.FormLayout

Summary: This patch ports fuzzy-clock's configuration window to QQC2 and Kirigami.FormLayout

Test Plan:
Before:

After:

Reviewers: Plasma, VDG, ngraham

Reviewed By: VDG, ngraham

Subscribers: abetts, plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D19747