chore: Remove unused code across multiple modules

src/Nethermind/Nethermind.Consensus.Clique/BlockHeaderExtensions.cs

@@ -1,8 +1,6 @@
 // SPDX-FileCopyrightText: 2022 Demerzel Solutions Limited
 // SPDX-License-Identifier: LGPL-3.0-only
 
-using System;
-using Nethermind.Blockchain;
 using Nethermind.Core;
 
 namespace Nethermind.Consensus.Clique
@@ -13,23 +11,6 @@ public static bool IsInTurn(this BlockHeader header)
         {
             return header.Difficulty == Clique.DifficultyInTurn;
         }
-
-        internal static Address[] ExtractSigners(BlockHeader blockHeader)
-        {
-            if (blockHeader.ExtraData is null)
-            {
-                throw new BlockchainException("Block header ExtraData cannot be null when extracting signers");
-            }
-
-            Span<byte> signersData = blockHeader.ExtraData.AsSpan(Clique.ExtraVanityLength, (blockHeader.ExtraData.Length - Clique.ExtraSealLength));
-            Address[] signers = new Address[signersData.Length / Address.Size];
-            for (int i = 0; i < signers.Length; i++)
-            {
-                signers[i] = new Address(signersData.Slice(i * 20, 20).ToArray());
-            }
-
-            return signers;
-        }
     }
 
     internal static class BlockExtensions