Add new block production endpoint

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -4601,7 +4601,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
 
     /// Load a beacon state from the database for block production. This is a long-running process
     /// that should not be performed in an `async` context.
-    fn load_state_for_block_production(
+    pub fn load_state_for_block_production(
         self: &Arc<Self>,
         slot: Slot,
     ) -> Result<(BeaconState<T::EthSpec>, Option<Hash256>), BlockProductionError> {