Full section notification for course enrolment

[eamonma]

Discussed in https://github.com/sqrl-planner/sqrl-client/discussions/79

^{Originally posted by GregSherman June 22, 2022} If you have a timetable that’s been made for a while and you go to look at it but a course has been filled up, maybe a notification can tell you and let's you choose another lecture section or ignore it.

This would be useful during course enrolment if data is updated live so you can quickly see backups, would also be useful to have that as a feature for auto schedules. If a section gets full it'll rearrange everything as little as possible to have a non full schedule.

Let's you get an edge on everyone else who has to scramble for backup schedules, would make sqrl the ideal use during course enrolment.