[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:
{F6690452}

After:
{F6690453}

Reviewers: #plasma, #vdg, ngraham

Reviewed By: #vdg, ngraham

Subscribers: abetts, plasma-devel

Tags: #plasma

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