feat: add introspection utils

[stipsan]

Highly experimental, not ready for review it's just surfaced here for transparency so the team is aware of where the code published to npm i groq-js@introspection is coming from.

It's being used to explore a source mapping concept in groqz.

The base is set to pkg-utils since it's the branch origin and using main would obfuscate the diff by showing tons of unrelated changes.