feat(layout): extend layout functionality

[NickTheWilder]

Starts the first part of #535 to hide specific rectangles based on the user's configuration file.
Inspired from the review comments in #545

Opened as a draft bc I've limited out on knowledge of the application (and rust).

TODO:

• Set the focused state to the first 'found' rectangle.
• Update default configuration file.
• Extend README.

Feel free to takeover and create a new branch or directly add commits here.

[NickTheWilder]

I see that the blob below sets the default focus state to the playlists, how can I import the config to this and set the initial focused state to the first 'found' percentage in the config?

spotify-player/spotify_player/src/state/ui/page.rs

Lines 231 to 241 in 8dcbc22

	impl LibraryPageUIState {
	pub fn new() -> Self {
	Self {
	playlist_list: ListState::default(),
	saved_album_list: ListState::default(),
	followed_artist_list: ListState::default(),
	focus: LibraryFocusState::Playlists,
	playlist_folder_id: 0,
	}
	}
	}

--

My thought was smth like

// ...
focus: match configs.app_config.layout.library {
    lib if lib.playlist_percent.is_some() => LibraryFocusState::Playlists,
    lib if lib.album_percent.is_some() => LibraryFocusState::SavedAlbums,
    lib if lib.artist_percent.is_some() => LibraryFocusState::FollowedArtists,
    _ => LibraryFocusState::Playlists,
},
// ...