Format all python sources using black and add it to pre-commit

[tmadlener]

BEGINRELEASENOTES

• Format all python sources using black and add it to pre-commit

ENDRELEASENOTES

[tmadlener]

I can squash the non-formatting changes into one commit so that the format one can be more easily be put into the ignore-revs file

[tmadlener]

Anyone with any objections for this?

[jmcarcell]

I prefer ' instead of " 😢

The choice should be the same for all the Key4hep repos with a single configuration file distributed everywhere. I guess it makes sense it's the black format since it's convenient to use it in key4hep-spack. So I don't have anything against this, once we agree I can do the formatting on all repos (not always easy depending on the number of open PRs...)

[tmadlener]

I prefer ' instead of " 😢

Not much we can do there without post-black hooks, I am afraid. I would just stay with whatever it does.

For the other repos I would gradually go through. I also think this should be a bit less painful than e.g. c++ and clang-format, because there is not too much python code.