saw-remote-api: Replace cryptonite dependency with crypton

[RyanGlScott]

The cryptonite family of packages are no longer actively maintained, and the crypton package aims to provide an alternative. We should replace these dependencies in saw-remote-api with crypton:

saw-script/saw-remote-api/saw-remote-api.cabal

Lines 49 to 50 in 4a695fb

	cryptonite,
	cryptonite-conduit,

There isn't a direct crypton equivalent of the cryptonite-conduit package, but we are only using the Crypto.Hash.Conduit module from that package, and the source code for that module is quite small. We could just as well inline this code into saw-remote-api.

[RyanGlScott]

There is now a crypton-conduit package, so we now have a drop-in replacement for cryptonite-conduit.