Replace black with ruff in tidy

[Kobzol]

ruff can both lint and format Python code (in fact, it should be a mostly drop-in replacement for black in terms of formatting), so it's not needed to use black anymore. This PR removes black and replaces it with ruff, to get rid of one Python dependency, and also to make Python formatting faster (although that's a small thing).

If we decide to merge this, we'll need to "reformat the world" - ruff is not perfectly compatible with black, and it also looks like black was actually ignoring some files before. I tried it locally (./x test tidy --extra-checks=py:fmt --bless) and it also reformatted some code in subtrees (e.g. clippy or rustc_codegen_gcc) - I'm not sure how to handle that.

[rustbot]

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[jieyouxu]

I think trimming the python deps (and also making py fmt slightly faster) is nice, will let Onur assess if the improvement is worth the churn of reformatting

[onur-ozkan]

If we decide to merge this, we'll need to "reformat the world"

I liked the changes in this PR, how much change do you mean with "world"? Can you make a draft PR to show that?