help request: monitor websocket connection status in apisix

### Description

We are performing traffic migration, transferring traffic to the APISIX gateway. During the migration process, we noticed a lack of monitoring for WebSocket connection status. How can we monitor the status of WebSocket connections?

### Environment

- APISIX version (run `apisix version`):
- Operating system (run `uname -a`):
- OpenResty / Nginx version (run `openresty -V` or `nginx -V`):
- etcd version, if relevant (run `curl http://127.0.0.1:9090/v1/server_info`):
- APISIX Dashboard version, if relevant:
- Plugin runner version, for issues related to plugin runners:
- LuaRocks version, for installation issues (run `luarocks --version`):

The issue names no file, test, or entry point. Begin by collecting the APISIX, operating system, OpenResty/Nginx, and etcd versions using the listed commands, then examine existing APISIX monitoring for WebSocket connections. Done would require a clearly documented and verifiable way to observe connection status, but the scope needs clarification first.

Written by the indexing model from the issue text.