applets/kickoff: put descriptions below titles, as we do elsewhere
Kickoff uses an unusual way of locating list items' descriptions: it puts them on the same line as the title, aligned to the right.
This saves vertical space but suffers from several issues:
- Because both labels need to inhabit the same line, a long title will cause the description to be elided into uselessness
- It's a different style than what we use for other list items with fundamentally the same set of data; we don't re-use users' existing familiarity with KDE-style list items that typically have the caption, subtitle, or description below the label/title
- Saving vertical space is not a win here because we want the applet to be touch-friendly, and short list items make that worse, not better
Accordingly, this MR changes the list items to put the descriptions under the labels to resolve those issues, like old Kickoff did. To avoid the result looking weird, non-sidebar list icon sizes are increased.
This MR is intended to improve the "Gwenview? What's a Gwenview?" effect that I am increasingly hearing people complain about. Despite the fact that list items have a caption that actually tells you what branded apps like Gwenview are, I think people are blind to it because they don't expect to see a description in that location. No other KDE list items do this and it's a fairly unusual style outside of KDE as well.
- This results in the layout having a strongly left-aligned style which could make it feel unbalanced. Not sure what we could do about that.