Dev environment + Typescript + Variables Improvements

[zsteinkamp]

• Ergonomics for dev environment (added node container to docker-compose along with VSCode devcontainer support)
• Hacking away at Typescript conformance
• Added prettier for automatic code formatting
• Utility methods targeting variables, with the intent of allowing the use of Nginx or environment variables for all configurable things.

[ivanitskiy]

LGTM with a few minor comments.

[ivanitskiy]

I see a missing part here, an updated examples/nginx.conf file, which documents all newly introduced (request)variables and associated env var and their respective defaults.

[ivanitskiy]

Let's rock and roll! Thank you for your contribution!