[idea]support for deno or other languages(simple directive is enough)

I like the nbdev ❤️ when I find it at first time.

This is just a quick idea.

Today, I find [deno can works in jupyter](https://deno.com/blog/v1.37) now, it is amazing.

- [Vega](https://github.com/rgbkrk/denotebooks/blob/main/VegaTime.ipynb)
- [Polars](https://github.com/rgbkrk/denotebooks/blob/main/10.2_Polar%20DataFrames.ipynb)

I believe if nbdev can support the basic function of other languages(or even Mojo🔥), it would be amazing. Even it support some simple code like, `# export` maybe `// export` in javascript, it would be useful.

I think other languages simply don’t have this type of development environment like nb and nbdev

No implementation files or tests are named in the issue. Start by reviewing nbdev’s current export-directive behavior and the linked Deno notebooks, then define the smallest supported cross-language case. Done should mean a basic directive such as `// export` works for Deno or another named language with coverage for that behavior.

Written by the indexing model from the issue text.