Migrate from ring to ed25519-dalek, take 2 (#3844)

* Migrate from ring to ed25519-dalek

* Move gen_keypair_file test to a more appropriate location

* Fixup bench-exchange and add helper fn for single deterministic keypair

* Update golden

bench-tps/src/bench.rs

@@ -68,7 +68,7 @@ pub fn do_bench_tps(config: Config) {
     let client = create_client(cluster_entrypoint.client_facing_addr(), FULLNODE_PORT_RANGE);
 
     let mut seed = [0u8; 32];
-    seed.copy_from_slice(&id.public_key_bytes()[..32]);
+    seed.copy_from_slice(&id.to_bytes()[..32]);
     let mut rnd = GenKeys::new(seed);
 
     println!("Creating {} keypairs...", tx_count * 2);