MultiServer, customserver, CI, Test: Fix problems in room hosting and test/simulate it (#3464)

* Test: add hosting simulation test

* WebHost: add weak typing to get_app()

* MultiServer: add typing to auto_saver_thread

* MultiServer: don't cancel task, properly end it

* customserver: stop auto-save thread from saving after shutdown

and make sure it stops, another potential memory leak

* MultiServer, customserver: make datapackage small again

* customserver: collect/finish room tasks

Hopefully fixes the memory leak we are seeing

* CI: test hosting

* Test: hosting: verify autohoster saves on Ctrl+C

* customserver: save when stopping via Ctrl+C

test/hosting/generate.py

@@ -0,0 +1,75 @@
+import json
+import sys
+import warnings
+from pathlib import Path
+from typing import Iterable, Union, TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from multiprocessing.managers import ListProxy  # noqa
+
+__all__ = [
+    "generate_local",
+]
+
+
+def _generate_local_inner(games: Iterable[str],
+                          dest: Union[Path, str],
+                          results: "ListProxy[Union[Path, BaseException]]") -> None:
+    original_argv = sys.argv
+    warnings.simplefilter("ignore")
+    try:
+        from tempfile import TemporaryDirectory
+
+        if not isinstance(dest, Path):
+            dest = Path(dest)
+
+        with TemporaryDirectory() as players_dir:
+            with TemporaryDirectory() as output_dir:
+                import Generate
+
+                for n, game in enumerate(games, 1):
+                    player_path = Path(players_dir) / f"{n}.yaml"
+                    with open(player_path, "w", encoding="utf-8") as f:
+                        f.write(json.dumps({
+                            "name": f"Player{n}",
+                            "game": game,
+                            game: {"hard_mode": "true"},
+                            "description": f"generate_local slot {n} ('Player{n}'): {game}",
+                        }))
+
+                # this is basically copied from test/programs/test_generate.py
+                # uses a reproducible seed that is different for each set of games
+                sys.argv = [sys.argv[0], "--seed", str(hash(tuple(games))),
+                            "--player_files_path", players_dir,
+                            "--outputpath", output_dir]
+                Generate.main()
+                output_files = list(Path(output_dir).glob('*.zip'))
+                assert len(output_files) == 1
+                final_file = dest / output_files[0].name
+                output_files[0].rename(final_file)
+                results.append(final_file)
+    except BaseException as e:
+        results.append(e)
+        raise e
+    finally:
+        sys.argv = original_argv
+
+
+def generate_local(games: Iterable[str], dest: Union[Path, str]) -> Path:
+    from multiprocessing import Manager, Process, set_start_method
+
+    try:
+        set_start_method("spawn")
+    except RuntimeError:
+        pass
+
+    manager = Manager()
+    results: "ListProxy[Union[Path, Exception]]" = manager.list()
+
+    p = Process(target=_generate_local_inner, args=(games, dest, results))
+    p.start()
+    p.join()
+    result = results[0]
+    if isinstance(result, BaseException):
+        raise Exception("Could not generate multiworld") from result
+    return result