Implement code/repo map

[yaroslavyaroslav]

The llms sucks with getting to know your code.

That's what RAG was invented for, the problem is RAG totally sucks as well.

Folks find some better approaches to retrieve enough context for llm based on syntax tree or lsp server.

https://aider.chat/2023/10/22/repomap.html

Such approach relies on function call feature, to make it who decides whether it's enough context to answer or do it need unveil yet another type declaration. So #17 should be implemented at first.