topic_edit: Store edit history in all the message affected.

Instead of just storing the edit history in the message which
triggered the topic edit, we store the edit history in all
the messages that changed. This helps users track the edit history
of a message more reliably.

zerver/lib/actions.py

@@ -4734,6 +4734,8 @@ def do_update_message(user_profile: UserProfile, message: Message,
             orig_topic_name=orig_topic_name,
             topic_name=topic_name,
             new_stream=new_stream,
+            edit_history_event=edit_history_event,
+            last_edit_time=timestamp
         )
         changed_messages += messages_list