Ensure payload envelope streamer always serves canonical envelopes after the split slot (#9085)

Co-Authored-By: Eitan Seri- Levi <eserilev@gmail.com>

Co-Authored-By: Eitan Seri-Levi <eserilev@ucsc.edu>

consensus/proto_array/src/proto_array_fork_choice.rs

@@ -1053,6 +1053,24 @@ impl ProtoArrayForkChoice {
             .unwrap_or(false)
     }
 
+    /// Returns the canonical payload status of a block, matching the decision
+    /// `get_head` would make between `(root, FULL)` and `(root, EMPTY)`.
+    pub fn get_canonical_payload_status<E: EthSpec>(
+        &self,
+        block_root: &Hash256,
+        current_slot: Slot,
+        proposer_boost_root: Hash256,
+        spec: &ChainSpec,
+    ) -> Result<PayloadStatus, Error> {
+        self.proto_array.get_canonical_payload_status::<E>(
+            *block_root,
+            current_slot,
+            proposer_boost_root,
+            &self.balances,
+            spec,
+        )
+    }
+
     /// Returns the weight of a given block.
     pub fn get_weight(&self, block_root: &Hash256) -> Option<u64> {
         let block_index = self.proto_array.indices.get(block_root)?;