[Kickoff] Always select previous category in Applications View when navigating backwards
Summary: Current version of the code positions view on the previous category but doesn't set the category itself. I think that selecting the previous category and not the first one is more convenient for keyboard navigation (when you accidentally miss the right category, for example).
Reviewers: Plasma, ngraham, hein
Reviewed By: Plasma, ngraham, hein
Differential Revision: https://phabricator.kde.org/D22866