feat(lyrics-plus): allow to change display of lyrics translation

[AndreasLrx]

This PR adds a new option to the lyrics-plus app to choose the display mode of the lyrics translation:

• Replace: Actual behavior, replacing the original lyrics with its translation
• Below: Display the original lyrics, and the translated line below in a lower opacity (as in the screen)

I'm not used to work on JS projects so I still have some small issues about this PR:

• Translated lines and behavior are repeated for each UnsyncedLyricsPage, SyncedExpandedLyricsPage SyncedLyricsPage and I feel like this could be refactored.
• I didn't now how to name the new option, because there is already a Display Mode so any suggestion to rename the option is welcomed
• When changing said option, it doesn't reload the lyrics div. It works when disabling and re-enabling the translation though.