Highlight currently playing playlist

[OpenSauce04]

Is your feature request related to a problem? Please describe.
If you don't currently have the playlist open, it can be difficult to tell which playlist is currently being played by ncspot, as there is no visual indication as there is with songs:

Describe the solution you'd like
The currently playing playlist should be highlighted in the same fashion as songs are

Describe alternatives you've considered
N/A

[bfahrenfort]

I'm looking at this to try and get plugged into the codebase because I'd like to start contributing. Do any maintainers know what it would entail?

I found the color change for ListItem in ListView's draw(), is it just a matter of implementing ListItem for ui::Playlist or should I implement Playable as well?