Add kernel detection for language support of runnable markdown cells

[JonGretar]

Closes #27757

Release Notes:

• List of runnable markdown cells is now based on detected jupyter kernels instead of hardcoded to Python and TypeScript

[JonGretar]

This would be my first real Rust code. Possibly it is lacking in quality. But it seems to work.

[rgbkrk]

Oooh, thank you. You'll need to address the clippy lints shown in the failing checks below.

[JonGretar]

Oooh, thank you. You'll need to address the clippy lints shown in the failing checks below.

Thanks @rgbkrk

Yeah I'm hitting a roadblock with the test_markdown_code_blocks test. Don't quite have the Rust skills.

I struggle with the modifying the tests as I need to either add kernels to the jupyter core programatically or mock the jupyter core somehow. And it seems tricky and not figuring it out.

[JonGretar]

Got the tests running. Thanks to generous help from Zed's new Agent mode. 😆 Don't know if the solution is to everyones liking. But it runs.

[JonGretar]

This is now ok I think.

Just for future reference. How do I run the syntax check locally? Or is there a single command to run all the same tests?

[rgbkrk]

Thanks @JonGretar!

[rgbkrk]

How do I run the syntax check locally?

Should be cargo xtask clippy