fix(tui): attribute TermResponse to source channel #40330

Problem: Attach-time terminal probes cannot distinguish responses from
different attached UIs.

Solution: Identify the UI by RPC channel id in `TermResponse` and make
`vim.tty.request()` filter responses by channel.

src/nvim/api/events.c

@@ -66,6 +66,6 @@ void nvim_ui_term_event(uint64_t channel_id, String event, Object value, Error *
 
     const String termresponse = value.data.string;
     set_vim_var_string(VV_TERMRESPONSE, termresponse.data, (ptrdiff_t)termresponse.size);
-    do_termresponse_autocmd(termresponse);
+    do_termresponse_autocmd(termresponse, channel_id);
   }
 }