Speed-up development with docker-compose

[anibalsolon]

Hi folks,

if interesting for you, I've set up a docker-compose to spin up the services used by openvsx locally. Gitpod is nice, and I've used a bit for my last PR, but having it locally helped me to better test the system. It is a pretty simple setup, probably needs some port bindings for debugging and so on.

@felipecrs you may find it easier to test the CLI using this.