Migrate formatter from yapf to ruff

[simon-mo]

The code format style of the Python project has over year migrated to black. https://black.readthedocs.io/en/stable/the_black_code_style/current_style.html

ruff is the tool are adopting for both the linter and formatter. ruff is significantly faster than black (see https://astral.sh/blog/the-ruff-formatter), which makes is order of magnitude faster than yapf.

It's best to review this PR by commit. 0a41f7d contains the only change needed. 05aa9e6 contains the resulting run of format.

After merging this and #1665, I will move the two commits in .git-blame-ignore-revs so git history is unchanged. https://github.blog/changelog/2022-03-24-ignore-commits-in-the-blame-view-beta/

[simon-mo]

After that I will post a comments to all PR concerning the change.

---

Action Required! We recently switch the formatter from yapf to ruff which should modernize the codebase. Your PR is affected. To prevent issues with merging your code, here's what you'll need to do:

1. Install ruff

pip install ruff==0.1.5

2. Format changed files with ruff

# Move to top-level directory.
cd $(git rev-parse --show-toplevel)
# Format changed files.
MERGEBASE="$(git merge-base upstream/master HEAD)"
if ! git diff --diff-filter=ACRM --quiet --exit-code "$MERGEBASE" -- '*.py' &>/dev/null; then
    git diff --name-only --diff-filter=ACRM "$MERGEBASE" -- '*.py' | xargs -P 5 \
        ruff format --respect-gitignore .
fi

3. Commit your changes.

git add --all
git commit -m "Format Python code with ruff"

4. Merge master into your branch.

git pull upstream main

Resolve merge conflicts (if necessary).

After running these steps, you'll have the updated format.sh.

Thank you!

[simon-mo]

Too late to do it :( This codebase is too big and too many in progress PRs.