Format Python code with black

[eriknw]

closes #2527

I also added .pre-commit-config.yaml to make this easier to use and match versions (for example, I kept using a newer flake8 locally). This uses the versions of black and flake8 that are in the rapids environment in the docker container. There's a lot more we can do with pre-commit, but I didn't want to be overzealous in this PR.

After this PR is merged, we should add a .git-blame-ignore-revs file so that I won't get blamed for everything :) . See:

• https://black.readthedocs.io/en/stable/guides/introducing_black_to_your_project.html#avoiding-ruining-git-blame
• https://docs.github.com/en/repositories/working-with-files/using-files/viewing-a-file#ignore-commits-in-the-blame-view

Once this is merged, existing PRs should probably run black (version 22.3.0) on their branch before merging 22.12 branch into their branch.

This changes the maximum line length to 88, which is the default for black

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (branch-22.12@9ee03f2). Click here to learn what that means.
Patch has no changes to coverable lines.

Additional details and impacted files

@@               Coverage Diff               @@
##             branch-22.12    #2778   +/-   ##
===============================================
  Coverage                ?   60.44%           
===============================================
  Files                   ?      111           
  Lines                   ?     6515           
  Branches                ?        0           
===============================================
  Hits                    ?     3938           
  Misses                  ?     2577           
  Partials                ?        0           

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.

[eriknw]

For sanity and convenience, this PR has a companion branch and PR #2780 that has the necessary changes before running black.

#2780 will be useful for keeping this branch up to date as PRs get merged, and for updating other PRs once this PR gets merge.

To verify the correctness of this PR, check out #2780 and run pre-commit run --all-files. The result should match this PR exactly.

[wence-]

FWIW, when this comes to merge, recommend squashing all the formatting commits and adding the final "change everything" commit hash to a top-level .git-blame-ignore-revs file. Then one can do git config blame.ignoreRevsFile .git-blame-ignore-revs and git blame will skip over this commit when assigning attribution to changed lines.

[rlratzel]

Assuming this contains the same changes as #2780 + changes as the result of running black

[eriknw]

Test failure is from a timeout in a test.

[rlratzel]

rerun tests

reason: timeout failure while running a test that doesn't appear related to the PR changes, assuming it's a transient CI problem.

[rlratzel]

@gpucibot merge