NowPlaying Improvements: seek buttons, play/pause track item syncing, replay button, shortcuts.

[esmersmith]

Here are the list of changes:

• Fast-forward and rewind buttons (10 seconds)
• Play/pause in the NowPlaying component is synced with the TrackItem button
• Replay button for when the song is finished
• shortcut keys for each button
  • space/enter for play/pause/replay
  • left for rewind
  • right for fast-forward

I think I would like to implement next/previous buttons as well, but that requires managing the track list state across different tabs, so I'll probably add that in a different PR. Let me know if you want anything changed.

[tranxuanthang]

I've just tested this on my machine and it works great!

Really love the replay feature, I admit I'm a bit annoyed that I can't replay the song in the current released version. Another small thing I'd love to have on the now playing is that, after the song is ended, we can click on any point on the seek bar to replay it at the selected point. If you want to help with that then it would be amazing (another PR is fine)!

One more useful feature is in-app volume control (as suggested in #38). This might require some additional commands from the Rust side. But asking more from you is probably too much, so feel free to continue with whatever you have planned or enjoy working on!

Anyway, this is a solid PR. Thank you for your hard work!