Use `Array.Empty()` in `System.Reflection.Metadata`. (#70862)

It is now available in all frameworks it targets.

src/libraries/System.Reflection.Metadata/src/System.Reflection.Metadata.csproj

@@ -109,7 +109,6 @@ System.Reflection.PortableExecutable.ManagedPEBuilder</PackageDescription>
     <Compile Include="System\Reflection\Internal\MemoryBlocks\StreamMemoryBlockProvider.cs" />
     <Compile Include="System\Reflection\Internal\Utilities\BitArithmetic.cs" />
     <Compile Include="System\Reflection\Internal\Utilities\StringUtils.cs" />
-    <Compile Include="System\Reflection\Internal\Utilities\EmptyArray.cs" />
     <Compile Include="System\Reflection\Internal\Utilities\EncodingHelper.cs" Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'" />
     <Compile Include="System\Reflection\Internal\Utilities\EncodingHelper.netcoreapp.cs" Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp'" />
     <Compile Include="System\Reflection\Internal\Utilities\StreamExtensions.netcoreapp.cs" Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp'" />

src/libraries/System.Reflection.Metadata/src/System/Reflection/Internal/Utilities/BlobUtilities.cs

@@ -16,7 +16,7 @@ public static byte[] ReadBytes(byte* buffer, int byteCount)
         {
             if (byteCount == 0)
             {
-                return EmptyArray<byte>.Instance;
+                return Array.Empty<byte>();
             }
 
             byte[] result = new byte[byteCount];

src/libraries/System.Reflection.Metadata/src/System/Reflection/Internal/Utilities/EmptyArray.cs

-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-
-namespace System.Reflection.Internal
-{
-    internal static class EmptyArray<T>
-    {
-#pragma warning disable CA1825 // Array.Empty<T>() doesn't exist in all configurations
-        internal static readonly T[] Instance = new T[0];
-#pragma warning restore CA1825
-    }
-}

src/libraries/System.Reflection.Metadata/src/System/Reflection/Metadata/Internal/BlobHeap.cs

@@ -98,7 +98,7 @@ internal byte[] GetBytes(BlobHandle handle)
             int numberOfBytes = Block.PeekCompressedInteger(offset, out bytesRead);
             if (numberOfBytes == BlobReader.InvalidCompressedInteger)
             {
-                return EmptyArray<byte>.Instance;
+                return Array.Empty<byte>();
             }
 
             return Block.PeekBytes(offset + bytesRead, numberOfBytes);