Fix naming consistency with attester crate.

Adjusted naming of files to ensure they match the name of the struct.
Also change the name of some structs so they don't look like tests.

eth2/attester/src/test_utils/local_signer.rs

@@ -0,0 +1,31 @@
+use crate::traits::Signer;
+use std::sync::RwLock;
+use types::{Keypair, Signature};
+
+/// A test-only struct used to simulate a Beacon Node.
+pub struct LocalSigner {
+    keypair: Keypair,
+    should_sign: RwLock<bool>,
+}
+
+impl LocalSigner {
+    /// Produce a new LocalSigner with signing enabled by default.
+    pub fn new(keypair: Keypair) -> Self {
+        Self {
+            keypair,
+            should_sign: RwLock::new(true),
+        }
+    }
+
+    /// If set to `false`, the service will refuse to sign all messages. Otherwise, all messages
+    /// will be signed.
+    pub fn enable_signing(&self, enabled: bool) {
+        *self.should_sign.write().unwrap() = enabled;
+    }
+}
+
+impl Signer for LocalSigner {
+    fn sign_attestation_message(&self, message: &[u8]) -> Option<Signature> {
+        Some(Signature::new(message, &self.keypair.sk))
+    }
+}