compose: Pass in stream_id to compose when editing scheduled message.

Earlier, we only passed in the stream name which isn't considered in
`compose_actions.start` when populating the recipient.

There was no visible bug since we first narrow to the correct stream and
then call `compose_actions.start`, but this was brittle since it would
not work if we open the compose box before narrowing.

web/src/scheduled_messages_ui.js

@@ -38,6 +38,7 @@ export function open_scheduled_message_in_compose(scheduled_msg, should_narrow_t
     if (scheduled_msg.type === "stream") {
         compose_args = {
             type: "stream",
+            stream_id: scheduled_msg.to,
             stream: sub_store.maybe_get_stream_name(scheduled_msg.to),
             topic: scheduled_msg.topic,
             content: scheduled_msg.content,