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.

crypto/ed448/src/lib.rs

@@ -14,3 +14,6 @@ pub use field::FieldElement;
 
 mod point;
 pub use point::Point;
+
+mod ciphersuite;
+pub use crate::ciphersuite::Ed448;