Made repository methods asynchronous. Simplified playlist repository. Use playlist manager in the app, and left playlist repository to only be used by the playlist manager.

Harmonia.Core/Extensions/ServiceCollectionExtensions.cs

@@ -24,4 +24,16 @@ public static class ServiceCollectionExtensions
 
         return services;
     }
+}
+
+public static class ServiceProviderExtensions
+{
+    public static async Task InitializeHarmoniaAsync(this IServiceProvider serviceProvider)
+    {
+        IPlaylistRepository playlistRepository = serviceProvider.GetRequiredService<IPlaylistRepository>();
+        await playlistRepository.InitializeAsync();
+
+        IPlaylistManager playlistManager = serviceProvider.GetRequiredService<IPlaylistManager>();
+        await playlistManager.InitializeAsync();
+    }
 }