feat: Put request rate limit at application server (#3857)

* feat: Put request rate limit at application server

This PR contains implementation for a blanket rate limiter at
application server level. Currently the allowed throughput is set high
only to be changed later as per the actual data gathered.

* Simplify implementation

1. Remove shutdown handler to purge rate limiter keys
2. Have separate keys for default and custom(route-based) rate limiters
3. Do not kill default rate limiter because it is not needed anymore due
   to (2) above

* Set 60s as default for rate limiting window

* Fix env types

server/types.ts

@@ -1,4 +1,5 @@
 import { Context } from "koa";
+import Redis from "@server/redis";
 import { FileOperation, Team, User } from "./models";
 
 export enum AuthenticationTypes {
@@ -297,3 +298,9 @@ export type Event =
   | UserEvent
   | ViewEvent
   | WebhookSubscriptionEvent;
+
+export type RateLimiterConfig = {
+  points: number;
+  duration: number;
+  storeClient: Redis;
+};