Rename too-many-positional{→-arguments}

[flying-sheep]

In pylint-dev/pylint#9842, they renamed too-many-positional to too-many-positional-arguments and implemented it.

If we at some point implement support for full names in addition to the codes we support already, this will affect us too.

PS: What’s the schedule for this rule coming out of preview?

[AlexWaygood]

Annoyingly, these are strictly-speaking parameters rather than arguments... but the new name seems strictly better than the old one, and it's useful to have the same name as pylint. PR welcome!