Implement operations on Dimension

[jacg]

This issue arose here: https://github.com/iliekturtles/uom/issues/295#issuecomment-1083247015.

In summary, it would be useful to implement various arithmetic operator traits on Dimension in order to facilitate creating/declaring Quantitys related to others, such as the-reciprocal-of-this-quantity or the-product-of-these-quantities ... but is it possible?

Note: the motivation for this is related to the motivation for #357.