- Add mode to buildXhttpExtra() so clients reading xtra param
(karing, etc.) receive the xhttp mode alongside other bidirectional
SplitHTTP fields. Previously mode was only a flat URL param and was
silently dropped when xtra was present.
- Add xhttp case to streamData() to strip acceptProxyProtocol and
server-only fields (noSSEHeader, scMaxBufferedPosts,
scStreamUpServerSecs, serverMaxHeaderBytes) from JSON sub configs.
- Sync frontend buildXhttpExtra() with the same mode addition.
Closes#4364
Abdalrahman
01a7dc807b