* 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
