支持服务管理 (#456)

* Support running as a Windows service.

* Optimize startup logic contro

* When running in a Windows service environment, delegate the termination of the program to the win_service_event_loop function.

* Remove the use of std::ffi::OsString at the top.

* Support  service manager

* Move the service-related features to be implemented in easytier-cli.

* Add a command line option work-dir to specify the working directory
Adjust the error handling logic

easytier/src/arch/windows.rs

@@ -152,4 +152,4 @@ pub fn setup_socket_for_win<S: AsRawSocket>(
     }
 
     Ok(())
-}
+}