Saved slots for timetables

[HollaG]

Is your feature request related to a problem? Please describe.

When testing multiple timetables it would be nice to have a quick switch feature for us to test different versions of a timetable

Describe the solution you'd like

Perhaps a solution could be implemented with the following ui features:

1. Button to save the current timetable
   a. On click, save the timetable as generated from the "share" url into localStorage along with a (user-generated) name
2. Dropdown to select a saved timetable from the existing list
   a. Each option in the dropdown will also provide a delete button
   b. Only saved timetables for the current selected academic year and semester will be shown, e.g. when "Special Term II" in the timetable planner is selected during AY23/24, only AY23/24 ST2 saved timetables will be shown
3. Warning upon attempting to load a timetable that isn't saved yet

Describe alternatives you've considered

This is just a overcomplicated notepad, but I think the ease of use might be beneficial.

Additional context

I'm willing to attempt working on this :)