Print/Output to file the final config used before the app starts

[hinogi]

Currently there is a lot of config injection happening when starting an app. It would be nice to have an option to output the final config either to use as a standalone entrypoint or even for migration to a different setup.
Also, it would help with debugging also if there is some misconfiguration happening. Simple example would be, with typescript support and multiple tsconfig.json files around, which one will be picked automatically.