Fixed Custom Events Loading Onto Map

[adcockdalton]

Summary

1. Add proper listeners for custom events updating in a manner analogous to that of classes in the Map directory

Test Plan

1. View map
2. Add new custom event with location (try RH, it's one of the acceptable and nearby ones)
3. See if change is reflected
4. See if change reflects when saved and you visit antalmanac.com/map

Issues

Closes #813

Future Followup

1. Not all locations are recognized for custom events on the map even though they are for classes (BS3, for example) and some don't even read on the calendar
2. Routes do not work for custom events (it is difficult to order them correctly with the classes due to how the indexes work)

[KevinWu098]

Thanks for the PR. Functionality is good, bug appears fixed. Just a comment on code quality/code duplication!

[KevinWu098]

For the future followup, I've opened #856 to address point 1 (good catch!), and for point 2, that should be added in #853

[KevinWu098]

LGTM 💖