Store historic class count in booking history

Currently, when a user is booked into a future class — let’s say it’s their 3rd class — the class view correctly shows “3rd class.” However, if you open a previous class they attended (which should show as their 2nd class), it still displays “3rd class.” This happens because the system currently shows only the live class count across all of the user’s classes.

We need to add functionality to display the correct historic class count in the booking history.