Add encoding and import support

osu.Game/IO/Archives/LegacyByteArrayReader.cs

@@ -0,0 +1,30 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Collections.Generic;
+using System.IO;
+
+namespace osu.Game.IO.Archives
+{
+    /// <summary>
+    /// Allows reading a single file from the provided stream.
+    /// </summary>
+    public class LegacyByteArrayReader : ArchiveReader
+    {
+        private readonly byte[] content;
+
+        public LegacyByteArrayReader(byte[] content, string filename)
+            : base(filename)
+        {
+            this.content = content;
+        }
+
+        public override Stream GetStream(string name) => new MemoryStream(content);
+
+        public override void Dispose()
+        {
+        }
+
+        public override IEnumerable<string> Filenames => new[] { Name };
+    }
+}