chore: Move rest of coloring.rs into secret-memory crate

Also removes the StoreSecret trait from cli.rs as it was
redundant.

fuzz/Cargo.toml

@@ -11,6 +11,7 @@ cargo-fuzz = true
 arbitrary = { workspace = true }
 libfuzzer-sys = { workspace = true }
 stacker = { workspace = true }
+rosenpass-secret-memory = { workspace = true }
 rosenpass-sodium = { workspace = true }
 rosenpass-ciphers = { workspace = true }
 rosenpass-to = { workspace = true }

fuzz/fuzz_targets/handle_msg.rs

@@ -3,8 +3,8 @@ extern crate rosenpass;
 
 use libfuzzer_sys::fuzz_target;
 
-use rosenpass::coloring::Secret;
 use rosenpass::protocol::CryptoServer;
+use rosenpass_secret_memory::Secret;
 use rosenpass_sodium::init as sodium_init;
 
 fuzz_target!(|rx_buf: &[u8]| {