Polish ToolBarApplicationHeader appearance
- Increase the toolbar height by 4 pixels, to make it look less cramped and give items inside it more vertical padding
- Give the navigation buttons some padding
Tested with Discover.
Reviewers: Kirigami, mart
Reviewed By: Kirigami, mart
Subscribers: abetts, Discover Software Store, plasma-devel, apol
Differential Revision: https://phabricator.kde.org/D10483