Add a cache layer to Docker

[mdashti]

This PR adds a cache later to Docker using cargo-chef. This change has a noticeable improvement in the turnaround time if someone is using Docker in their development cycle.

[levkk]

Not too familiar with cargo chef. Is it ok to include this in the production image? If not, we can always create a Dockerfile.dev.

[levkk]

You may want a debug build here.

[mdashti]

Thanks. Done.

[mdashti]

@levkk cargo chef is definitely the accepted docker cache layer, but I'm also not sure about its production grade. From their repo:

cargo-chef was initially developed for the deployment chapter of [Zero to Production In Rust](https://zero2prod.com/), a hands-on introduction to backend development using the Rust programming language.

Which might mean initially was not meant to be for production, but it is now.

Anyways, your suggestion makes sense. Thanks.

[levkk]

LGTM!