feat: Add support for multi-day events

[KevinWu098]

I also noticed, while looking at events.json, that neither of our methods work for multi-day events like WebJam, so I’m thinking we could get around this by splitting up the time property in each event object into separate startTime and endTime properties, and figure out a good way to represent it in the front-end depending on whether it’s a single or multi-day event. Might be something for a future PR though, since it’s a bit more complex

Originally posted by @ryanmohta in #88 (comment)

This would include updating events.json and the UI for the events page for multi-day events.