Port away from old Kirigami List Items

Reason for the change

The old Kirigami list delegates are going away for KF6; we need to port away from them.

Depends on frameworks/qqc2-desktop-style!304 (merged) and frameworks/kirigami!1304 (merged).

Test plan

Used Elisa for a day or so with both desktop and Mobile mode with these changes. No visual or functional changes found.

Bugs fixed

https://bugs.kde.org/show_bug.cgi?id=474580