Fixes #365
Fixes #366

• NOTE: With the implementation of this feature, I've introduced a new AlbumArt model.
  • This abstracts the previously used byte[] for FrontAlbumArt and BackAlbumArt into a full object which contains and exposes the underlying byte[] for the image, but also contains properties for an image's Width, Height, MimeType and AlbumArtType.
  • The Width and Height are processed and provided by the ImageSharp library.
  • MimeType is provided by ATL.PictureInfo.
  • An ATL.PictureInfo representation of the AlbumArt object is also accessible via the object's ATLPictureInfo property which manages and exposes this ATL object to prevent having to create it more times than needed when actually setting ATL.Track's picture.

Fixes #370
Fixes #372

Screenshots for new feature designs can be seen on individual issues themselves