Studio Chat: Open to newest message first

Original Title: Chat window should auto-open and scroll to the newest message.

When a parent, teacher, or studio admin opens the chat feature:

1. The chat sidebar pane should automatically open

2. Selected message threads should automatically scroll to the newest message

This automatic behavior is preferable because parents, who may not be very tech-savvy, shouldn't need to know how to manually open the menu and scroll down to find the information they need.