ws client: handle RX in blocks

This patch was actually produced by Gemini 2.5 + fixdiff

It was difficult to get this result and took several days plus the writing
of fixdiff.  It would have been quicker to do it myself, but maybe that
will no longer be true for one reason or another before long.

This is a private link to the chat session for traceability
https://aistudio.google.com/prompts/1sGwAzomeHgEs81mbimXL9mKMfpvfGDQV

https://libwebsockets.org/git/fixdiff

FWIW it still passes sai tests with this patch.  But currently only putting
it on main for testing.

Co-developed-by: Gemini 2.5 Pro

Author: lws-team

lib/core-net/private-lib-core-net.h

@@ -1208,6 +1208,9 @@ lws_has_buffered_out(struct lws *wsi);
 lws_handling_result_t LWS_WARN_UNUSED_RESULT
 lws_ws_client_rx_sm(struct lws *wsi, unsigned char c);
 
+lws_handling_result_t LWS_WARN_UNUSED_RESULT
+lws_ws_client_rx_pump(struct lws *wsi, const void *in, size_t len);
+
 lws_parser_return_t LWS_WARN_UNUSED_RESULT
 lws_parse(struct lws *wsi, unsigned char *buf, int *len);