feat: split money into parts

[barredterra]

Add a method to easily split a Money object into a number of parts, ensuring that the sum of the parts equals the original amount:

>>> Money('10.00', 'USD').split(3)
[Money(3.34, "USD"), Money(3.33, "USD"), Money(3.33, "USD")]

>>> sum(Money('10', 'USD').split(3)) == Money('10', 'USD')
True

Note that the precision of the split amounts will be the same as the original amount.