refactor: move VrfResult to common and use for Shelley block header (#835)

Author: agaffney

ledger/babbage/babbage.go

@@ -140,12 +140,6 @@ func (b *BabbageBlock) Utxorpc() *utxorpc.Block {
 	return block
 }
 
-type BabbageBlockHeaderVrfResult struct {
-	cbor.StructAsArray
-	Output []byte
-	Proof  []byte
-}
-
 type BabbageBlockHeader struct {
 	cbor.StructAsArray
 	cbor.DecodeStoreCbor
@@ -157,7 +151,7 @@ type BabbageBlockHeader struct {
 		PrevHash      common.Blake2b256
 		IssuerVkey    common.IssuerVkey
 		VrfKey        []byte
-		VrfResult     BabbageBlockHeaderVrfResult
+		VrfResult     common.VrfResult
 		BlockBodySize uint64
 		BlockBodyHash common.Blake2b256
 		OpCert        struct {

ledger/common/vrf.go

@@ -0,0 +1,25 @@
+// Copyright 2024 Blink Labs Software
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package common
+
+import (
+	"github.com/blinklabs-io/gouroboros/cbor"
+)
+
+type VrfResult struct {
+	cbor.StructAsArray
+	Output []byte
+	Proof  []byte
+}

ledger/shelley/shelley.go

@@ -140,8 +140,8 @@ type ShelleyBlockHeader struct {
 		PrevHash             common.Blake2b256
 		IssuerVkey           common.IssuerVkey
 		VrfKey               []byte
-		NonceVrf             interface{}
-		LeaderVrf            interface{}
+		NonceVrf             common.VrfResult
+		LeaderVrf            common.VrfResult
 		BlockBodySize        uint64
 		BlockBodyHash        common.Blake2b256
 		OpCertHotVkey        []byte