[Astronomical Calendar Plugin] Port to QQC2+Kirigami Formlayout
Summary:
- Port to QQC2+Kirigami FormLayout style
- Use standard import names
- Adjust strings to fit in the FormLayout style
Test Plan:
Reviewers: VDG, Plasma, ndavis
Reviewed By: VDG, ndavis
Subscribers: ndavis, plasma-devel
Tags: Plasma
Maniphest Tasks: T10586
Differential Revision: https://phabricator.kde.org/D21193