Migrate Python formatting to ruff from black

[kieran-ryan]

Migrates Python formatting to ruff from black to speed up formatting by multiples (see below benchmarks); and for robustness improvements; such as those applied by the formatting of this merge request to string formatting, trailing commas rather than a mixture with and without; improved formatting of arguments, whitespace line handling, etc. - though all of which are included with later releases of various Python formatter tools.

The ruff formatter is "designed as a drop-in replacement for Black". The caching in particular improves development workflows with tools such as IDEs and hooks.

Ruff's default configuration is a superset of those specified by the black configuration within the pyproject.toml; and thus only required extension to the custom path src/buildstream/_protos.

Raising based on observation and in case of interest.

Benchmarks

Cold Runs

Black	Ruff	Delta	% Change
13.86s	2.07s	11.79s	-85%

Screenshots

Black

Ruff

Warm Runs

Black	Ruff	Delta	% Change
12.31s	0.54s	11.77s	-95.6%

Screenshots

Black

Ruff

[cs-shadow]

hi @kieran-ryan , I'd be in favor of this change in principle.

Although it may be good to float this on the mailing list first as it may be a little bit of disruptive change for people who may be in the habit of running Black.

Especially because it seems like Ruff would do more reformatting than "just" a drop-in replacement.