macosx: Enable 'Reveal in Finder' feature for albums, artists, and genres

This was previously only enabled for songs.

Screen_Recording_2022-07-20_at_01.38.28

modules/gui/macosx/library/VLCLibraryDataTypes.h

@@ -121,6 +121,7 @@ extern const long long int VLCMediaLibraryMediaItemDurationDenominator;
 @property (readonly) unsigned int numberOfAlbums;
 @property (readonly) unsigned int numberOfTracks;
 @property (readonly) NSArray <VLCMediaLibraryAlbum *> *albums;
+@property (readonly) NSArray <VLCMediaLibraryMediaItem *> *tracksAsMediaItems;
 
 @end