feat(chat): Improve progress serializer
feat(chat): Improve progress serializer

Consider additional messages in progress calculation
Adding "started" and "done" fields to lessons in lesson list in LessonSerializer

cjlee112/socraticqs2,raccoongang/socraticqs2,cjlee112/socraticqs2,cjlee112/socraticqs2,raccoongang/socraticqs2,cjlee112/socraticqs2,raccoongang/socraticqs2,raccoongang/socraticqs2