Create ruff_notebook crate

[charliermarsh]

Summary

This PR moves ruff/jupyter into its own ruff_notebook crate. Beyond the move itself, there were a few challenges:

1. ruff_notebook relies on the source map abstraction. I've moved the source map into ruff_diagnostics, since it doesn't have any dependencies on its own and is used alongside diagnostics.
2. ruff_notebook has a couple tests for end-to-end linting and autofixing. I had to leave these tests in ruff itself.
3. We had code in ruff/jupyter that relied on Python lexing, in order to provide a more targeted error message in the event that a user saves a .py file with a .ipynb extension. I removed this in order to avoid a dependency on the parser, it felt like it wasn't worth retaining just for that dependency.

Test Plan

cargo test

[MichaReiser]

I don't have a better recommendation but moving source map to diagnostic feels a bit off because it isn't the only possible use case for source maps. For example, source maps can be used to move the IDE cursor to the right position after applying fixes. However, that requires extracting our fix infrastructure which is rather involved and even Fix is defined in Diagnostic

[github-actions]

PR Check Results

Ecosystem

✅ ecosystem check detected no changes.

[dhruvmanila]

That was quick, thanks!

We might want to name it something along the lines of ruff_notebook as Jupyter is actually just a frontend while this crate would ideally handle notebooks in general (#6140)