Improve `holidays.constants` multi-line import sorting

[arkid15r]

Keep week days and months multi-line imports ordered according to the date/time context (which is more readable taking into account the nature of python-holidays package).

I would have dreamt to see those holidays.constants multi-line import move to the isort format (definitely nicer and more readable than the black's version).

Originally posted by @dr-prodigy in https://github.com/dr-prodigy/python-holidays/issues/722#issuecomment-1268560210