Add duties service to validator

validator_client/src/duties/traits.rs

@@ -0,0 +1,16 @@
+use super::EpochDuties;
+use bls::PublicKey;
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum BeaconNodeError {
+    RemoteFailure(String),
+    DecodeFailure,
+}
+
+pub trait BeaconNode: Send + Sync {
+    fn request_shuffling(
+        &self,
+        epoch: u64,
+        public_key: &PublicKey,
+    ) -> Result<Option<EpochDuties>, BeaconNodeError>;
+}