fix(api): retain WebSocket endpoint paths and query parameters (#3999)

## Summary

Preserve WebSocket endpoint paths and query parameters when using a
custom base URL.

## Changes

- Keep the Responses endpoint when the base URL includes a query string.
- Preserve query parameters on an explicit WebSocket base URL for
Responses, Realtime, and Live.
- Let connection query parameters override the selected URL, and the
selected URL override client defaults. Preserve repeated URL query
values.

Co-authored-by: markstuart-oai <323302876+markstuart-oai@users.noreply.github.com>