Add the ByteSize measure

[nfrisby]

The new ByteSize measure should be used for all byte size summations relevant to the Cardano chain.

• It has checked arithmetic, with a pure representation of overflow.
• It still has a Monoid instance that will be useful for finger trees.

The other types defined in the module should be used for recording/transmitting the result of summations that did not overflow.

[nfrisby]

TODO test suite