Update vendored httpx-ws to upstream v0.9.0 (0341891)

The initial vendoring in #1042 accidentally used frankie567/httpx-ws@6bc568b
(v0.6.2 era, October 2024), missing 80 upstream commits. This ports every
upstream change from that point to the current tip, frankie567/httpx-ws@0341891
(v0.9.0 + 6 commits). See discussion #1066.

Highlights:
- Serialize stream writes with a write lock (httpx-ws#29)
- Rebuild the async session on anyio.AsyncContextManagerMixin, fixing the
  asyncio hang on exit after cancellation and cancel scope corruption
  (httpx-ws#108); requires anyio>=4.10
- Rewrite ASGIWebSocketTransport on a task group and anyio streams instead of
  a blocking portal and queue.Queue
- Support the WebSocket Denial Response ASGI extension
- Add a configurable initial_receive_timeout with a clear error when the
  server never accepts
- Raise TimeoutError instead of queue.Empty on sync receive timeout
- Handle end of stream and closing-state keepalive pings properly
- Add class-based WebSocketClient/AsyncWebSocketClient with session_class
  support (kept off connect_ws/aconnect_ws, where mypy cannot infer the
  TypeVar default through the contextmanager decorator)

Two fixes not in upstream: register aclose before the initial receive so a
never-accepting app does not leak memory object streams, and cover the
double-__aenter__ guard with a test.

Author: Kludex

docs/websockets.md

@@ -66,7 +66,7 @@ The `receive` methods block until a message is available. Pass a `timeout` in se
 >>> ws.receive_text(timeout=2.0)
 ```
 
-If no message arrives in time, the sync session raises `queue.Empty`, while the async session raises `TimeoutError`.
+If no message arrives in time, `TimeoutError` is raised.
 
 If the received message doesn't match the expected type, `WebSocketInvalidTypeReceived` is raised.
 

src/httpx2/httpx2/websockets/__init__.py

@@ -4,7 +4,13 @@
 Copyright (c) 2021 François Voron, MIT License (https://github.com/frankie567/httpx-ws/blob/main/LICENSE).
 """
 
-from ._api import AsyncWebSocketSession, JSONMode, WebSocketSession
+from ._api import (
+    AsyncWebSocketClient,
+    AsyncWebSocketSession,
+    JSONMode,
+    WebSocketClient,
+    WebSocketSession,
+)
 from ._exceptions import (
     HTTPXWSException,
     WebSocketDisconnect,
@@ -16,9 +22,11 @@
 
 __all__ = [
     "ASGIWebSocketTransport",
+    "AsyncWebSocketClient",
     "AsyncWebSocketSession",
     "HTTPXWSException",
     "JSONMode",
+    "WebSocketClient",
     "WebSocketDisconnect",
     "WebSocketInvalidTypeReceived",
     "WebSocketNetworkError",