[feature request] support cuckaroo and cuckatoo variants

[sebseb7]

https://github.com/tromp/cuckoo/tree/master/src/cuckaroo

https://github.com/swap-dev/cuckaroo_portability_testcase

[tynes]

Handshake is no longer using Cuckoo Cycle as a Proof of Work, so it is not very likely that this repo will be updated to support those variants. See https://github.com/handshake-org/hsd/issues/24 and https://github.com/handshake-org/hsd/issues/71