Separate API endpoints and Socket endpoints into different files and load in index.ts

[AlexanderWangY]

As of right now, our backend's endpoints are all stored in index.ts which is a monolith of code which gets pretty confusing. We'd like you to help us sort them our into separate files, one for API related functions and one for Socket related functions!

Some tips:

• Use the router functionality given by expressJS and app.use it in the index.ts (possibly?)
• Make initializing sockets a function that is called once in index.ts on startup?

Move other files into their respective folder's and make sure that if something breaks, we can pinpoint exactly whether it was in the sockets or api!

[fmcubium]

Taking on this task!