Add model downloading endpoint. (#4248)

* Add model downloading endpoint.

* Move client session init to async function.

* Break up large function.

* Send "download_progress" as websocket event.

* Fixed

* Fixed.

* Use async mock.

* Move server set up to right before run call.

* Validate that model subdirectory cannot contain relative paths.

* Add download_model test checking for invalid paths.

* Remove DS_Store.

* Consolidate DownloadStatus and DownloadModelResult

* Add progress_interval as an optional parameter.

* Use tuple type from annotations.

* Use pydantic.

* Update comment.

* Revert "Use pydantic."

This reverts commit 7461e8eb00.

* Add new line.

* Add newline EOF.

* Validate model filename as well.

* Add comment to not reply on internal.

* Restrict downloading to safetensor files only.

main.py

@@ -261,6 +261,7 @@ if __name__ == "__main__":
         call_on_start = startup_server
 
     try:
+        loop.run_until_complete(server.setup())
         loop.run_until_complete(run(server, address=args.listen, port=args.port, verbose=not args.dont_print_server, call_on_start=call_on_start))
     except KeyboardInterrupt:
         logging.info("\nStopped server")