kcms/recentfiles: Modernize grid view code and styling
This code is pretty old, and uses handmade delegates that look inconsistent and dated. Modernize it to use ItemDelegates, and improve the layout code to account for narrow or mobile windows.
Requires frameworks/qqc2-desktop-style!453 (merged) since that's what makes icon-over-text style delegates possible with our QQC2 style.
Pay no attention to the weird data in this view; that's a separate issue: https://bugs.kde.org/show_bug.cgi?id=502523
Edited by Nate Graham