[Feature] Subtitle position/height offset

[kk-min]

Hello, I was wondering if it would be possible to implement a subtitle position/height offset that can be helpful for "viewing" audiobooks. When viewing audio files (i.e. no visuals, just black screen) in the media player with subtitles, the subtitles default to the bottom of the page. It would be helpful if they were in the middle instead (Although I know there is the Transcript Playback Mode, the black screen is desirable for an immersive experience with audio). It might also be helpful for people viewing visual media to adjust the height if it is too close to the bottom of the screen.

I would love to contribute but unfortunately I don't have much experience with Flutter/Dart. If this feature is desirable to add and is easy enough for a newcomer to attempt, I'm willing to give it a shot with some guidance.