Fix issues from D24798 comments by @davidedmundson
Summary: Lower QQC2 version to minimum requirement. Add context to i18nc function. Cannot use i18ncp because the number isn't integer.
Reviewers: Plasma, davidedmundson
Reviewed By: Plasma, davidedmundson
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D25319