feat: add ExecutionPayloadFieldV2 into ExecutionPayload (#1858)

crates/rpc-types-engine/src/payload.rs

@@ -68,6 +68,14 @@ impl ExecutionPayloadFieldV2 {
             Self::V2(payload) => payload.payload_inner,
         }
     }
+
+    /// Converts this payload variant into the corresponding [ExecutionPayload]
+    pub fn into_payload(self) -> ExecutionPayload {
+        match self {
+            Self::V1(payload) => ExecutionPayload::V1(payload),
+            Self::V2(payload) => ExecutionPayload::V2(payload),
+        }
+    }
 }
 
 /// This is the input to `engine_newPayloadV2`, which may or may not have a withdrawals field.
@@ -830,6 +838,12 @@ impl From<ExecutionPayloadV2> for ExecutionPayload {
     }
 }
 
+impl From<ExecutionPayloadFieldV2> for ExecutionPayload {
+    fn from(payload: ExecutionPayloadFieldV2) -> Self {
+        payload.into_payload()
+    }
+}
+
 impl From<ExecutionPayloadV3> for ExecutionPayload {
     fn from(payload: ExecutionPayloadV3) -> Self {
         Self::V3(payload)