Implement api schema and docs

[Timothy-Gonzalez]

Resolves #218
Resolves #219
Resolves #222

This is a massive pr, and massive is an understatement. In essense, every endpoint now uses a special specification middleware.

This middleware takes in zod schemas and other metadata in order to both validate incoming requests, type the req and res express objects, and generate documentation with openapi + swagger.

Here's an example:

eventsRouter.get(
    "/staff/",
    specification({
        method: "get",
        path: "/event/staff/",
        tag: Tag.EVENT,
        role: Role.STAFF,
        summary: "Gets all staff events",
        responses: {
            [StatusCode.SuccessOK]: {
                description: "The events",
                schema: PublicEventsSchema,
            },
            [StatusCode.ClientErrorNotFound]: {
                description: "Couldn't find the event specified",
                schema: EventNotFoundErrorSchema,
            },
        },
    }),
    async (_req, res) => {
        const events = await Models.Event.find({ isStaff: true });
        const filteredEvents = events.map(filterEvent);
        return res.status(StatusCode.SuccessOK).send({ events: filteredEvents });
    },
);

There are several breaking changes from this:
changes:

• Reverted v2:
  • GET /user/v2-qr/ -> GET /user/qr/
  • GET /shop/v2/ -> GET /shop/
• Changed user following to be consistent with other following endpoints:
  • GET /user/following/ properly returns followed events as { userId: "123", following: ["event1",...] } instead of { userId: "123", events: ["event1",...] }
• Changed event following ids to be path parameters instead of body ones:
  • PUT /user/follow/ with { eventId: "event1"} to PUT /user/follow/event1/
  • PUT /user/unfollow/ with { eventId: "event1"} to DELETE /user/unfollow/event1/
• Fixed point shop buying to include all item properties:
  • POST /shop/item/buy/ with { itemName: "Jacket" } to { name: "Jacket", ..all additional item properties }
• Fixed the weirdest endpoint, admin rsvp behavior. No changes required to apps, just admin site for this one.
  • GET /admission/rsvp/ no longer returns all rsvps just for staff and only current user for non-staff (why in the first place...) - admin site will need to use new GET /admission/rsvp/staff/ endpoint to get all rsvps
  • other changes that were on unused endpoints

There's still a lot to clean up, but at least now we're consistent. The biggest move going forward is adding more tests, as it was much harder to do these changes without them.

[aletya]

HUGE PR! I dug through specification.ts, specification-validator.ts, and model.ts in depth and skimmed through the rest. The code really is a ton cleaner and intuitive which will make future changes easier. Appreciate the work to make everything consistent, especially for the req/res validation and documentation! LGTM :)