WebHost: allow APPlayerContainers from "custom" worlds to be displayed in rooms (#4981)

Gives WebHost the ability to verify that a patch file is an APPlayerContainer (defined by #4331 as a APContainer containing the "player" field), and allowed it to display any patch file that it can verify is an APPlayerContainer.

worlds/Files.py

@@ -6,6 +6,7 @@ import zipfile
 from enum import IntEnum
 import os
 import threading
+from io import BytesIO
 
 from typing import ClassVar, Dict, List, Literal, Tuple, Any, Optional, Union, BinaryIO, overload, Sequence
 
@@ -70,6 +71,18 @@ class AutoPatchExtensionRegister(abc.ABCMeta):
 container_version: int = 6
 
 
+def is_ap_player_container(game: str, data: bytes, player: int):
+    if not zipfile.is_zipfile(BytesIO(data)):
+        return False
+    with zipfile.ZipFile(BytesIO(data), mode='r') as zf:
+        if "archipelago.json" in zf.namelist():
+            manifest = json.loads(zf.read("archipelago.json"))
+            if "game" in manifest and "player" in manifest:
+                if game == manifest["game"] and player == manifest["player"]:
+                    return True
+    return False
+
+
 class InvalidDataError(Exception):
     """
     Since games can override `read_contents` in APContainer,