Support explicitly passing config file using CLI option or env var

[yehonatanz]

It would be great if once could pass a --node-dev-config or NODE_DEV_CONFIG path. My use case is a monorepo where I'd love to have a single .node-dev.json instead of duplicating it for each app.

Alternatively, recursive resolution of .node-dev.json file, searching parent dirs of the current script would also address my use case.

I'm open to implementing whatever option we choose myself 😊