Smash Ciphersuite definitions into their own crates

Uses dalek-ff-group for Ed25519 and Ristretto. Uses minimal-ed448 for Ed448.
Adds ciphersuite-kp256 for Secp256k1 and P-256.

coordinator/src/tributary/signing_protocol.rs

@@ -63,9 +63,10 @@ use rand_core::OsRng;
 
 use blake2::{Digest, Blake2s256};
 
+use dalek_ff_group::Ristretto;
 use ciphersuite::{
   group::{ff::PrimeField, GroupEncoding},
-  Ciphersuite, Ristretto,
+  Ciphersuite,
 };
 use dkg_musig::musig;
 use frost::{FrostError, dkg::Participant, ThresholdKeys, sign::*};