Gracefully Shutdown Server on Exit

[srilman]

Right now, shutting down the server (via ^C) will forcefully close any goroutines that are running, including any that are processing requests. Ideally, the server should receive the signal, wait to finish processing requests while denying new requests, and then shutdown.

A tutorial on how to implement this in Golang: https://www.rudderstack.com/blog/implementing-graceful-shutdown-in-go/