fix: 优化项目代码

1、修复部分字幕下载问题
2、修复自定义aria2设置出错问题

DownKyi/CustomControl/AsyncImageLoader/IAsyncImageLoader.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Threading.Tasks;
+using Avalonia.Media.Imaging;
+
+namespace DownKyi.CustomControl.AsyncImageLoader;
+
+public interface IAsyncImageLoader : IDisposable
+{
+    /// <summary>
+    ///     Loads image
+    /// </summary>
+    /// <param name="url">Target url</param>
+    /// <returns>Bitmap</returns>
+    public Task<Bitmap?> ProvideImageAsync(string url);
+}