Add pygrep-hooks and mdformat to pre-commit hooks

[Armavica]

Towards #8239. This mainly addresses problems in rst and markdown files.

[max-sixty]

Overall looks great!

We should check some of those, I added a couple of comments, though not a complete review.

To the extent that some might interfere with mypy or ruff, etc, that's not good — we don't want to be in a situation where code can't get through both checkers. Are we OK there?

The markdown & rst checkers look overall great!

[headtr1ck]

Why don't we instead try to rely on ruff and enable these rules there? Many seems supported already, rules start with PGH*.

[max-sixty]

Why don't we instead try to rely on ruff and enable these rules there? Many seems supported already, rules start with PGH*.

Definitely preferable for the python ones. (though formatting non-python files would still be part of this sort of effort...)

[Armavica]

Thank you for all your comments, I switched to prettier which seems to do a less surprising job in many cases. I also deselected the pygrep-hooks that are already checked by ruff.