compose: Open send later modal when user accepts the warning on scheduling message.

When the user has a wildcard @-mention we show a warning if the stream has more than
15 members. When the user clicks "Yes, schedule" and confirms the intend to schedule
the message we open the send later modal to let user choose scheduling time.

Fixes #25426.

web/src/compose_validate.js

@@ -251,6 +251,7 @@ function show_wildcard_warnings(opts) {
         button_text,
         hide_close_button: true,
         classname,
+        scheduling_message: opts.scheduling_message,
     });
 
     // only show one error for any number of @all or @everyone mentions