feat: 添加部分简单 API，相应修改程序入口的初始化流程 (#251)

crates/bili_sync/src/task/mod.rs

@@ -0,0 +1,5 @@
+mod http_server;
+mod video_downloader;
+
+pub use http_server::http_server;
+pub use video_downloader::video_downloader;