[v3-alpha] Add v2 tools to Jupyternaut

[dlqqq]

Problem

Jupyternaut should provide capabilities of Jupyter AI available in v2.

Proposed Solution

• Add tool for RAG, learning files & querying learned files

• Add tool for fixing errors in notebooks

• Generate notebooks / Python files

Additional context

We will prefer using natural-language routing for these features. We do not plan on bringing back default slash commands unless a need arises (e.g. if NL routing doesn't work as well as we expect).