Reintroduce ICS generation

aep-schedule-generator/Cargo.lock

aep-schedule-generator/Cargo.toml

aep-schedule-generator/alternance.csv

aep-schedule-generator/src/algorithm/schedule.rs

aep-schedule-generator/src/algorithm/taken_course.rs

aep-schedule-generator/src/bin/ics.rs

aep-schedule-generator/src/data/time/calendar.rs

aep-schedule-generator/src/data/time/day.rs

aep-schedule-generator/src/data/time/mod.rs

aep-schedule-generator/src/icalendar/calendar.rs

aep-schedule-generator/src/icalendar/dates.rs

aep-schedule-generator/src/icalendar/dates_builder.rs

aep-schedule-generator/src/icalendar/mod.rs

aep-schedule-generator/src/lib.rs

aep-schedule-website/Cargo.lock

aep-schedule-website/alternance.csv

aep-schedule-website/src/backend/routes.rs

aep-schedule-website/src/backend/state.rs

aep-schedule-website/src/frontend/components/schedule.rs

aep-schedule-website/style/main.scss