Feature/lyrics

[Naapperas]

This PR adds a new screen for the user to see the currently playing track's lyrics and optionally save them to their system.
Closes #1076.

This behavior should be configurable by the user, i.e.:

• the location for saving lyrics should be configurable;
• the users preferred fetcher(s) should be configurable. For instance, they may want to only use MusixMatch or they may want to have several options available, with the next fetcher being used in case the previous is unavailable/invalid

Missing features:

• Lyric fetching (need to think about how to correctly abstract the fetching mechanism to use several implementations)
• • Although this is currently working, there are formatting issues which I believe are easy to fix. Only tested for a single API, which does not contain everything.
• Lyric caching (for performance reasons, re-fetching the same lyrics over and over is not ideal)
• Configurable Lyrics fetcher
• Lyrics page update (no access to music change event, at least none I could find, need to "manually" update, aka re-enter the view)
• Asynchronous lyrics fetching (I looked into Cursive Async View but could not get it to work, still need to investigate further)

This is a follow up on #1108